diff --git a/book/src/mutants.md b/book/src/mutants.md
index e102c680..6acf818c 100644
--- a/book/src/mutants.md
+++ b/book/src/mutants.md
@@ -89,5 +89,14 @@ too prone to generate false positives, for example when unsigned integers are co
 ## Unary operators
 
 Unary operators are deleted in expressions like `-a` and `!a`.
-They are not currently replaced with other unary operators because they are too prone to 
+They are not currently replaced with other unary operators because they are too prone to
 generate unviable cases (e.g. `!1.0`, `-false`).
+
+## Match arms
+
+Entire match arms are deleted in match expressions when a wildcard pattern is present in one of the arms.
+Match expressions without a wildcard pattern would be too prone to unviable mutations of this kind.
+
+## Match arm guards
+
+Match arm guard expressions are replaced with `true` and `false`.
diff --git a/src/fnvalue.rs b/src/fnvalue.rs
index 5a49d87d..3e2d691a 100644
--- a/src/fnvalue.rs
+++ b/src/fnvalue.rs
@@ -202,9 +202,6 @@ fn type_replacements(type_: &Type, error_exprs: &[Expr]) -> impl Iterator<Item =
                     .collect_vec()
             }
         },
-        Type::Tuple(TypeTuple { elems, .. }) if elems.is_empty() => {
-            vec![quote! { () }]
-        }
         Type::Tuple(TypeTuple { elems, .. }) => {
             // Generate the cartesian product of replacements of every type within the tuple.
             elems
diff --git a/src/mutant.rs b/src/mutant.rs
index e08facd5..3163b452 100644
--- a/src/mutant.rs
+++ b/src/mutant.rs
@@ -26,6 +26,10 @@ pub enum Genre {
     /// Replace `==` with `!=` and so on.
     BinaryOperator,
     UnaryOperator,
+    /// Delete match arm.
+    MatchArm,
+    /// Replace the expression of a match arm guard with a fixed value.
+    MatchArmGuard,
 }
 
 /// A mutation applied to source code.
@@ -131,33 +135,43 @@ impl Mutant {
             style(s.to_string())
         }
         let mut v: Vec<StyledObject<String>> = Vec::new();
-        if self.genre == Genre::FnValue {
-            v.push(s("replace "));
-            let function = self
-                .function
-                .as_ref()
-                .expect("FnValue mutant should have a function");
-            v.push(s(&function.function_name).bright().magenta());
-            if !function.return_type.is_empty() {
-                v.push(s(" "));
-                v.push(s(&function.return_type).magenta());
-            }
-            v.push(s(" with "));
-            v.push(s(self.replacement_text()).yellow());
-        } else {
-            if self.replacement.is_empty() {
-                v.push(s("delete "));
-            } else {
+        match self.genre {
+            Genre::FnValue => {
                 v.push(s("replace "));
-            }
-            v.push(s(self.original_text()).yellow());
-            if !self.replacement.is_empty() {
+                let function = self
+                    .function
+                    .as_ref()
+                    .expect("FnValue mutant should have a function");
+                v.push(s(&function.function_name).bright().magenta());
+                if !function.return_type.is_empty() {
+                    v.push(s(" "));
+                    v.push(s(&function.return_type).magenta());
+                }
                 v.push(s(" with "));
-                v.push(s(&self.replacement).bright().yellow());
+                v.push(s(self.replacement_text()).yellow());
             }
-            if let Some(function) = &self.function {
-                v.push(s(" in "));
-                v.push(s(&function.function_name).bright().magenta());
+            Genre::MatchArmGuard => {
+                v.push(s("replace match guard with "));
+                v.push(s(self.replacement_text()).yellow());
+            }
+            Genre::MatchArm => {
+                v.push(s("delete match arm"));
+            }
+            _ => {
+                if self.replacement.is_empty() {
+                    v.push(s("delete "));
+                } else {
+                    v.push(s("replace "));
+                }
+                v.push(s(self.original_text()).yellow());
+                if !self.replacement.is_empty() {
+                    v.push(s(" with "));
+                    v.push(s(&self.replacement).bright().yellow());
+                }
+                if let Some(function) = &self.function {
+                    v.push(s(" in "));
+                    v.push(s(&function.function_name).bright().magenta());
+                }
             }
         }
         v
diff --git a/src/visit.rs b/src/visit.rs
index cdc937fc..715454b2 100644
--- a/src/visit.rs
+++ b/src/visit.rs
@@ -595,6 +595,53 @@ impl<'ast> Visit<'ast> for DiscoveryVisitor<'_> {
         };
         syn::visit::visit_expr_unary(self, i);
     }
+
+    fn visit_expr_match(&mut self, i: &'ast syn::ExprMatch) {
+        let _span = trace_span!("match", line = i.span().start().line).entered();
+
+        // While it's not currently possible to annotate expressions with custom attributes, this
+        // limitation could be lifted in the future.
+        if attrs_excluded(&i.attrs) {
+            trace!("match excluded by attrs");
+            return;
+        }
+
+        let has_catchall = i
+            .arms
+            .iter()
+            .any(|arm| matches!(arm.pat, syn::Pat::Wild(_)));
+        if has_catchall {
+            i.arms
+                .iter()
+                // Don't mutate the wild arm, because that will likely be unviable, and also
+                // skip it if a guard is present, because the replacement of the guard with 'false'
+                // below is logically equivalent to removing the arm.
+                .filter(|arm| !matches!(arm.pat, syn::Pat::Wild(_)) && arm.guard.is_none())
+                .for_each(|arm| {
+                    self.collect_mutant(arm.span().into(), &quote! {}, Genre::MatchArm);
+                });
+        } else {
+            trace!("match has no `_` pattern");
+        }
+
+        i.arms
+            .iter()
+            .flat_map(|arm| &arm.guard)
+            .for_each(|(_if, guard_expr)| {
+                self.collect_mutant(
+                    guard_expr.span().into(),
+                    &quote! { true },
+                    Genre::MatchArmGuard,
+                );
+                self.collect_mutant(
+                    guard_expr.span().into(),
+                    &quote! { false },
+                    Genre::MatchArmGuard,
+                );
+            });
+
+        syn::visit::visit_expr_match(self, i);
+    }
 }
 
 // Get the span of the block excluding the braces, or None if it is empty.
@@ -1084,4 +1131,122 @@ mod test {
             "#}
         );
     }
+
+    #[test]
+    fn mutate_match_arms_with_fallback() {
+        let options = Options::default();
+        let mutants = mutate_source_str(
+            indoc! {"
+                fn main() {
+                    match x {
+                        X::A => {},
+                        X::B => {},
+                        _ => {},
+                    }
+                }
+            "},
+            &options,
+        )
+        .unwrap();
+        assert_eq!(
+            mutants
+                .iter()
+                .filter(|m| m.genre == Genre::MatchArm)
+                .map(|m| m.name(true))
+                .collect_vec(),
+            [
+                "src/main.rs:3:9: delete match arm",
+                "src/main.rs:4:9: delete match arm",
+            ]
+        );
+    }
+
+    #[test]
+    fn skip_match_arms_without_fallback() {
+        let options = Options::default();
+        let mutants = mutate_source_str(
+            indoc! {"
+                fn main() {
+                    match x {
+                        X::A => {},
+                        X::B => {},
+                    }
+                }
+            "},
+            &options,
+        )
+        .unwrap();
+
+        let empty: &[&str] = &[];
+        assert_eq!(
+            mutants
+                .iter()
+                .filter(|m| m.genre == Genre::MatchArm)
+                .map(|m| m.name(true))
+                .collect_vec(),
+            empty
+        );
+    }
+
+    #[test]
+    fn mutate_match_guard() {
+        let options = Options::default();
+        let mutants = mutate_source_str(
+            indoc! {"
+                fn main() {
+                    match x {
+                        X::A if foo() => {},
+                        X::A => {},
+                        X::B => {},
+                        X::C if bar() => {},
+                    }
+                }
+            "},
+            &options,
+        )
+        .unwrap();
+        assert_eq!(
+            mutants
+                .iter()
+                .filter(|m| m.genre == Genre::MatchArmGuard)
+                .map(|m| m.name(true))
+                .collect_vec(),
+            [
+                "src/main.rs:3:17: replace match guard with true",
+                "src/main.rs:3:17: replace match guard with false",
+                "src/main.rs:6:17: replace match guard with true",
+                "src/main.rs:6:17: replace match guard with false",
+            ]
+        );
+    }
+
+    #[test]
+    fn skip_removing_match_arm_with_guard() {
+        let options = Options::default();
+        let mutants = mutate_source_str(
+            indoc! {"
+                fn main() {
+                    match x {
+                        X::A if foo() => {},
+                        X::A => {},
+                        _ => {},
+                    }
+                }
+            "},
+            &options,
+        )
+        .unwrap();
+        assert_eq!(
+            mutants
+                .iter()
+                .filter(|m| matches!(m.genre, Genre::MatchArmGuard | Genre::MatchArm))
+                .map(|m| m.name(true))
+                .collect_vec(),
+            [
+                "src/main.rs:4:9: delete match arm",
+                "src/main.rs:3:17: replace match guard with true",
+                "src/main.rs:3:17: replace match guard with false",
+            ]
+        );
+    }
 }
diff --git a/src/workspace.rs b/src/workspace.rs
index 79e81db7..97872dc9 100644
--- a/src/workspace.rs
+++ b/src/workspace.rs
@@ -201,10 +201,6 @@ impl Workspace {
         // in that case we'll just fall back to everything, for lack of a better option.
         // TODO: Use the new cargo_metadata API that doesn't panic?
         match catch_unwind(|| metadata.workspace_default_packages()) {
-            Ok(default_packages) if default_packages.is_empty() => {
-                debug!("manifest has no explicit default packages");
-                PackageSelection::All
-            }
             Ok(default_packages) => {
                 let default_package_names: Vec<&str> = default_packages
                     .iter()
diff --git a/testdata/many_patterns/src/binops.rs b/testdata/many_patterns/src/binops.rs
index 4a5ae69e..fd0bc3b8 100644
--- a/testdata/many_patterns/src/binops.rs
+++ b/testdata/many_patterns/src/binops.rs
@@ -6,6 +6,14 @@ pub fn binops() {
     a -= 2;
     a *= 3;
     a /= 2;
+
+    let mut b;
+    b = a < 0;
+    b = a <= 0;
+    b = a > 0;
+    b = a >= 0;
+    b = a == 0;
+    b = a != 0;
 }
 
 pub fn bin_assign() -> i32 {
@@ -15,5 +23,6 @@ pub fn bin_assign() -> i32 {
     a &= 0x0f;
     a >>= 4;
     a <<= 1;
+    a %= 1;
     a
 }
diff --git a/testdata/workspace_default_members/Cargo_test.toml b/testdata/workspace_default_members/Cargo_test.toml
new file mode 100644
index 00000000..ebb5e5c1
--- /dev/null
+++ b/testdata/workspace_default_members/Cargo_test.toml
@@ -0,0 +1,6 @@
+# This workspace has default-members set, which influences which packages are mutated by default.
+
+[workspace]
+members = ["main", "excluded"]
+default-members = ["main"]
+resolver = "2"
diff --git a/testdata/workspace_default_members/excluded/Cargo_test.toml b/testdata/workspace_default_members/excluded/Cargo_test.toml
new file mode 100644
index 00000000..b1d58b61
--- /dev/null
+++ b/testdata/workspace_default_members/excluded/Cargo_test.toml
@@ -0,0 +1,10 @@
+[package]
+name = "excluded"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+mutants = "0.0.3"
diff --git a/testdata/workspace_default_members/excluded/src/main.rs b/testdata/workspace_default_members/excluded/src/main.rs
new file mode 100644
index 00000000..42b7812b
--- /dev/null
+++ b/testdata/workspace_default_members/excluded/src/main.rs
@@ -0,0 +1,3 @@
+fn main() -> i32 {
+    100
+}
\ No newline at end of file
diff --git a/testdata/workspace_default_members/main/Cargo_test.toml b/testdata/workspace_default_members/main/Cargo_test.toml
new file mode 100644
index 00000000..b8d2f40d
--- /dev/null
+++ b/testdata/workspace_default_members/main/Cargo_test.toml
@@ -0,0 +1,10 @@
+[package]
+name = "main"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+mutants = "0.0.3"
diff --git a/testdata/workspace_default_members/main/src/main.rs b/testdata/workspace_default_members/main/src/main.rs
new file mode 100644
index 00000000..1873f2f9
--- /dev/null
+++ b/testdata/workspace_default_members/main/src/main.rs
@@ -0,0 +1,6 @@
+const X: u32 = 2 + 1;
+
+#[test]
+fn test() {
+    assert_eq!(X, 3);
+}
diff --git a/tests/main.rs b/tests/main.rs
index f428de98..605f239b 100644
--- a/tests/main.rs
+++ b/tests/main.rs
@@ -45,6 +45,18 @@ fn show_version() {
         .stdout(predicates::str::is_match(r"^cargo-mutants \d+\.\d+\.\d+(-.*)?\n$").unwrap());
 }
 
+#[test]
+fn show_help() {
+    // Asserting on the entire help message would be a bit too annoying to maintain.
+    run()
+        .args(["mutants", "--help"])
+        .assert()
+        .success()
+        .stdout(predicates::str::contains(
+            "Usage: cargo mutants [OPTIONS] [-- <CARGO_TEST_ARGS>...]",
+        ));
+}
+
 #[test]
 fn uses_cargo_env_var_to_run_cargo_so_invalid_value_fails() {
     let tmp_src_dir = copy_of_testdata("well_tested");
diff --git a/tests/snapshots/list__list_mutants_in_all_trees_as_json.snap b/tests/snapshots/list__list_mutants_in_all_trees_as_json.snap
index c0aac58e..412a899f 100644
--- a/tests/snapshots/list__list_mutants_in_all_trees_as_json.snap
+++ b/tests/snapshots/list__list_mutants_in_all_trees_as_json.snap
@@ -2205,7 +2205,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2218,8 +2218,8 @@ snapshot_kind: text
     "replacement": "()",
     "span": {
       "end": {
-        "column": 12,
-        "line": 8
+        "column": 16,
+        "line": 16
       },
       "start": {
         "column": 5,
@@ -2235,7 +2235,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2265,7 +2265,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2295,7 +2295,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2325,7 +2325,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2355,7 +2355,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2385,7 +2385,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2415,7 +2415,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2445,7 +2445,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2475,7 +2475,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2505,7 +2505,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2535,7 +2535,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2565,7 +2565,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2595,7 +2595,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2625,7 +2625,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2655,7 +2655,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2685,7 +2685,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2715,7 +2715,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2745,7 +2745,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2775,7 +2775,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2805,7 +2805,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2835,7 +2835,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2865,7 +2865,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2895,7 +2895,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2925,7 +2925,7 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 9
+          "line": 17
         },
         "start": {
           "column": 1,
@@ -2947,6 +2947,246 @@ snapshot_kind: text
       }
     }
   },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "==",
+    "span": {
+      "end": {
+        "column": 12,
+        "line": 11
+      },
+      "start": {
+        "column": 11,
+        "line": 11
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": ">",
+    "span": {
+      "end": {
+        "column": 12,
+        "line": 11
+      },
+      "start": {
+        "column": 11,
+        "line": 11
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": ">",
+    "span": {
+      "end": {
+        "column": 13,
+        "line": 12
+      },
+      "start": {
+        "column": 11,
+        "line": 12
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "==",
+    "span": {
+      "end": {
+        "column": 12,
+        "line": 13
+      },
+      "start": {
+        "column": 11,
+        "line": 13
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "<",
+    "span": {
+      "end": {
+        "column": 12,
+        "line": 13
+      },
+      "start": {
+        "column": 11,
+        "line": 13
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "<",
+    "span": {
+      "end": {
+        "column": 13,
+        "line": 14
+      },
+      "start": {
+        "column": 11,
+        "line": 14
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "!=",
+    "span": {
+      "end": {
+        "column": 13,
+        "line": 15
+      },
+      "start": {
+        "column": 11,
+        "line": 15
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "binops",
+      "return_type": "",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 17
+        },
+        "start": {
+          "column": 1,
+          "line": 1
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "==",
+    "span": {
+      "end": {
+        "column": 13,
+        "line": 16
+      },
+      "start": {
+        "column": 11,
+        "line": 16
+      }
+    }
+  },
   {
     "file": "src/binops.rs",
     "function": {
@@ -2955,11 +3195,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -2969,11 +3209,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 6,
-        "line": 18
+        "line": 27
       },
       "start": {
         "column": 5,
-        "line": 12
+        "line": 20
       }
     }
   },
@@ -2985,11 +3225,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -2999,11 +3239,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 6,
-        "line": 18
+        "line": 27
       },
       "start": {
         "column": 5,
-        "line": 12
+        "line": 20
       }
     }
   },
@@ -3015,11 +3255,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3029,11 +3269,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 6,
-        "line": 18
+        "line": 27
       },
       "start": {
         "column": 5,
-        "line": 12
+        "line": 20
       }
     }
   },
@@ -3045,11 +3285,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3059,11 +3299,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 13
+        "line": 21
       },
       "start": {
         "column": 7,
-        "line": 13
+        "line": 21
       }
     }
   },
@@ -3075,11 +3315,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3089,11 +3329,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 13
+        "line": 21
       },
       "start": {
         "column": 7,
-        "line": 13
+        "line": 21
       }
     }
   },
@@ -3105,11 +3345,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3119,11 +3359,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 14
+        "line": 22
       },
       "start": {
         "column": 7,
-        "line": 14
+        "line": 22
       }
     }
   },
@@ -3135,11 +3375,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3149,11 +3389,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 14
+        "line": 22
       },
       "start": {
         "column": 7,
-        "line": 14
+        "line": 22
       }
     }
   },
@@ -3165,11 +3405,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3179,11 +3419,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 15
+        "line": 23
       },
       "start": {
         "column": 7,
-        "line": 15
+        "line": 23
       }
     }
   },
@@ -3195,11 +3435,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3209,11 +3449,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 9,
-        "line": 15
+        "line": 23
       },
       "start": {
         "column": 7,
-        "line": 15
+        "line": 23
       }
     }
   },
@@ -3225,11 +3465,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3239,11 +3479,11 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 10,
-        "line": 16
+        "line": 24
       },
       "start": {
         "column": 7,
-        "line": 16
+        "line": 24
       }
     }
   },
@@ -3255,11 +3495,11 @@ snapshot_kind: text
       "span": {
         "end": {
           "column": 2,
-          "line": 19
+          "line": 28
         },
         "start": {
           "column": 1,
-          "line": 11
+          "line": 19
         }
       }
     },
@@ -3269,11 +3509,71 @@ snapshot_kind: text
     "span": {
       "end": {
         "column": 10,
-        "line": 17
+        "line": 25
       },
       "start": {
         "column": 7,
-        "line": 17
+        "line": 25
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "bin_assign",
+      "return_type": "-> i32",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 28
+        },
+        "start": {
+          "column": 1,
+          "line": 19
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "/=",
+    "span": {
+      "end": {
+        "column": 9,
+        "line": 26
+      },
+      "start": {
+        "column": 7,
+        "line": 26
+      }
+    }
+  },
+  {
+    "file": "src/binops.rs",
+    "function": {
+      "function_name": "bin_assign",
+      "return_type": "-> i32",
+      "span": {
+        "end": {
+          "column": 2,
+          "line": 28
+        },
+        "start": {
+          "column": 1,
+          "line": 19
+        }
+      }
+    },
+    "genre": "BinaryOperator",
+    "package": "cargo-mutants-testdata-many-patterns",
+    "replacement": "+=",
+    "span": {
+      "end": {
+        "column": 9,
+        "line": 26
+      },
+      "start": {
+        "column": 7,
+        "line": 26
       }
     }
   }
@@ -9849,3 +10149,44 @@ snapshot_kind: text
   }
 ]
 ```
+
+## testdata/workspace_default_members
+
+```json
+[
+  {
+    "file": "main/src/main.rs",
+    "function": null,
+    "genre": "BinaryOperator",
+    "package": "main",
+    "replacement": "-",
+    "span": {
+      "end": {
+        "column": 19,
+        "line": 1
+      },
+      "start": {
+        "column": 18,
+        "line": 1
+      }
+    }
+  },
+  {
+    "file": "main/src/main.rs",
+    "function": null,
+    "genre": "BinaryOperator",
+    "package": "main",
+    "replacement": "*",
+    "span": {
+      "end": {
+        "column": 19,
+        "line": 1
+      },
+      "start": {
+        "column": 18,
+        "line": 1
+      }
+    }
+  }
+]
+```
diff --git a/tests/snapshots/list__list_mutants_in_all_trees_as_text.snap b/tests/snapshots/list__list_mutants_in_all_trees_as_text.snap
index b66d933f..7688b670 100644
--- a/tests/snapshots/list__list_mutants_in_all_trees_as_text.snap
+++ b/tests/snapshots/list__list_mutants_in_all_trees_as_text.snap
@@ -209,17 +209,27 @@ src/binops.rs:7:7: replace *= with += in binops
 src/binops.rs:7:7: replace *= with /= in binops
 src/binops.rs:8:7: replace /= with %= in binops
 src/binops.rs:8:7: replace /= with *= in binops
-src/binops.rs:12:5: replace bin_assign -> i32 with 0
-src/binops.rs:12:5: replace bin_assign -> i32 with 1
-src/binops.rs:12:5: replace bin_assign -> i32 with -1
-src/binops.rs:13:7: replace |= with &= in bin_assign
-src/binops.rs:13:7: replace |= with ^= in bin_assign
-src/binops.rs:14:7: replace ^= with |= in bin_assign
-src/binops.rs:14:7: replace ^= with &= in bin_assign
-src/binops.rs:15:7: replace &= with |= in bin_assign
-src/binops.rs:15:7: replace &= with ^= in bin_assign
-src/binops.rs:16:7: replace >>= with <<= in bin_assign
-src/binops.rs:17:7: replace <<= with >>= in bin_assign
+src/binops.rs:11:11: replace < with == in binops
+src/binops.rs:11:11: replace < with > in binops
+src/binops.rs:12:11: replace <= with > in binops
+src/binops.rs:13:11: replace > with == in binops
+src/binops.rs:13:11: replace > with < in binops
+src/binops.rs:14:11: replace >= with < in binops
+src/binops.rs:15:11: replace == with != in binops
+src/binops.rs:16:11: replace != with == in binops
+src/binops.rs:20:5: replace bin_assign -> i32 with 0
+src/binops.rs:20:5: replace bin_assign -> i32 with 1
+src/binops.rs:20:5: replace bin_assign -> i32 with -1
+src/binops.rs:21:7: replace |= with &= in bin_assign
+src/binops.rs:21:7: replace |= with ^= in bin_assign
+src/binops.rs:22:7: replace ^= with |= in bin_assign
+src/binops.rs:22:7: replace ^= with &= in bin_assign
+src/binops.rs:23:7: replace &= with |= in bin_assign
+src/binops.rs:23:7: replace &= with ^= in bin_assign
+src/binops.rs:24:7: replace >>= with <<= in bin_assign
+src/binops.rs:25:7: replace <<= with >>= in bin_assign
+src/binops.rs:26:7: replace %= with /= in bin_assign
+src/binops.rs:26:7: replace %= with += in bin_assign
 ```
 
 ## testdata/missing_test
@@ -551,3 +561,10 @@ main2/src/main.rs:10:5: replace triple_3 -> i32 with 0
 main2/src/main.rs:10:5: replace triple_3 -> i32 with 1
 main2/src/main.rs:10:5: replace triple_3 -> i32 with -1
 ```
+
+## testdata/workspace_default_members
+
+```
+main/src/main.rs:1:18: replace + with -
+main/src/main.rs:1:18: replace + with *
+```
diff --git a/tests/workspace.rs b/tests/workspace.rs
index 7e35a86d..8d21b3f1 100644
--- a/tests/workspace.rs
+++ b/tests/workspace.rs
@@ -6,7 +6,7 @@ use std::fs::{self, create_dir, read_to_string, write};
 
 use insta::assert_snapshot;
 use itertools::Itertools;
-use predicates::prelude::predicate;
+use predicates::{prelude::predicate, str::PredicateStrExt};
 use pretty_assertions::assert_eq;
 use serde_json::json;
 
@@ -295,6 +295,25 @@ fn baseline_test_respects_package_options() {
     );
 }
 
+#[test]
+fn in_workspace_only_default_members_are_mutated_if_present() {
+    let tmp = copy_of_testdata("workspace_default_members");
+    run()
+        .args(["mutants", "--no-shuffle", "--list", "-d"])
+        .arg(tmp.path())
+        .assert()
+        .success()
+        .stdout(
+            predicates::ord::eq(
+                "\
+            main/src/main.rs:1:18: replace + with -\n\
+            main/src/main.rs:1:18: replace + with *\n\
+            ",
+            )
+            .normalize(),
+        );
+}
+
 #[test]
 fn cross_package_tests() {
     // This workspace has two packages, one of which contains the tests.