diff --git a/src/extension/alterschema/CMakeLists.txt b/src/extension/alterschema/CMakeLists.txt
index 506936b59..ee37e8cf2 100644
--- a/src/extension/alterschema/CMakeLists.txt
+++ b/src/extension/alterschema/CMakeLists.txt
@@ -90,7 +90,8 @@ sourcemeta_library(NAMESPACE sourcemeta PROJECT core NAME alterschema
     linter/unevaluated_items_default.h
     linter/unevaluated_properties_default.h
     linter/unsatisfiable_max_contains.h
-    linter/unsatisfiable_min_properties.h)
+    linter/unsatisfiable_min_properties.h
+    linter/then_false.h)
 
 if(SOURCEMETA_CORE_INSTALL)
   sourcemeta_library_install(NAMESPACE sourcemeta PROJECT core NAME alterschema)
diff --git a/src/extension/alterschema/alterschema.cc b/src/extension/alterschema/alterschema.cc
index bd2af6027..23ee04633 100644
--- a/src/extension/alterschema/alterschema.cc
+++ b/src/extension/alterschema/alterschema.cc
@@ -109,6 +109,7 @@ inline auto APPLIES_TO_POINTERS(std::vector<Pointer> &&keywords)
 #include "linter/property_names_default.h"
 #include "linter/property_names_type_default.h"
 #include "linter/simple_properties_identifiers.h"
+#include "linter/then_false.h"
 #include "linter/title_description_equal.h"
 #include "linter/title_trailing_period.h"
 #include "linter/title_trim.h"
@@ -150,6 +151,7 @@ auto add(SchemaTransformer &bundle, const AlterSchemaMode mode) -> void {
   bundle.add<NotFalse>();
   bundle.add<ThenEmpty>();
   bundle.add<ElseEmpty>();
+  bundle.add<ThenFalse>();
   bundle.add<ThenWithoutIf>();
   bundle.add<DependenciesPropertyTautology>();
   bundle.add<DependentRequiredTautology>();
diff --git a/src/extension/alterschema/linter/then_false.h b/src/extension/alterschema/linter/then_false.h
new file mode 100644
index 000000000..1fcd0279d
--- /dev/null
+++ b/src/extension/alterschema/linter/then_false.h
@@ -0,0 +1,52 @@
+class ThenFalse final : public SchemaTransformRule {
+public:
+  ThenFalse()
+      : SchemaTransformRule{
+            "then_false",
+            "`Setting the `then` keyword to the false schema is a convoluted "
+            "way of negating the `if` subschema, which you can more cleanly "
+            "represent using the `not` keyword"} {};
+
+  [[nodiscard]] auto
+  condition(const JSON &schema, const JSON &, const Vocabularies &vocabularies,
+            const SchemaFrame &, const SchemaFrame::Location &,
+            const SchemaWalker &, const SchemaResolver &) const
+      -> SchemaTransformRule::Result override {
+    ONLY_CONTINUE_IF(
+        vocabularies.contains_any(
+            {Vocabularies::Known::JSON_Schema_2020_12_Applicator,
+             Vocabularies::Known::JSON_Schema_2019_09_Applicator,
+             Vocabularies::Known::JSON_Schema_Draft_7}) &&
+        schema.is_object() && schema.defines("if") && schema.defines("then") &&
+        schema.at("then").is_boolean() && !schema.at("then").to_boolean() &&
+        is_schema(schema.at("if")) &&
+        !(schema.at("if").is_boolean() && schema.at("if").to_boolean()) &&
+        (!schema.defines("else") ||
+         (schema.at("else").is_boolean() && schema.at("else").to_boolean())) &&
+        (!schema.at("if").is_object() ||
+         std::all_of(schema.at("if").as_object().begin(),
+                     schema.at("if").as_object().end(),
+                     [&schema](const auto &entry) {
+                       return !schema.defines(entry.first);
+                     })) &&
+        std::all_of(schema.as_object().begin(), schema.as_object().end(),
+                    [](const auto &entry) {
+                      return entry.first == "$schema" || entry.first == "if" ||
+                             entry.first == "then" || entry.first == "else";
+                    }));
+
+    if (schema.defines("else")) {
+      return APPLIES_TO_KEYWORDS("then", "if", "else");
+    } else {
+      return APPLIES_TO_KEYWORDS("then", "if");
+    }
+  }
+
+  auto transform(JSON &schema, const Result &) const -> void override {
+    auto if_schema = schema.at("if");
+    schema.erase("if");
+    schema.erase("then");
+    schema.erase("else");
+    schema.assign("not", std::move(if_schema));
+  }
+};
diff --git a/test/alterschema/alterschema_lint_2019_09_test.cc b/test/alterschema/alterschema_lint_2019_09_test.cc
index deb3544a2..fb48cc152 100644
--- a/test/alterschema/alterschema_lint_2019_09_test.cc
+++ b/test/alterschema/alterschema_lint_2019_09_test.cc
@@ -3997,3 +3997,179 @@ TEST(AlterSchema_lint_2019_09,
   EXPECT_TRUE(result.first);
   EXPECT_EQ(traces.size(), 0);
 }
+
+TEST(AlterSchema_lint_2019_09, then_false_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false,
+    "else": true
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": true,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": true,
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_4) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": false,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_5) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_6) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "not": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_false_7) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
diff --git a/test/alterschema/alterschema_lint_2020_12_test.cc b/test/alterschema/alterschema_lint_2020_12_test.cc
index 911217cdb..225cb8539 100644
--- a/test/alterschema/alterschema_lint_2020_12_test.cc
+++ b/test/alterschema/alterschema_lint_2020_12_test.cc
@@ -4452,6 +4452,182 @@ TEST(AlterSchema_lint_2020_12,
   EXPECT_EQ(document, expected);
 }
 
+TEST(AlterSchema_lint_2020_12, then_false_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false,
+    "else": true
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": true,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": true,
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_4) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": false,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_5) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_6) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "not": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_false_7) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
 TEST(AlterSchema_lint_2020_12, embedded_resource_draft7) {
   sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
     "$schema": "https://json-schema.org/draft/2020-12/schema",
diff --git a/test/alterschema/alterschema_lint_draft7_test.cc b/test/alterschema/alterschema_lint_draft7_test.cc
index f7c05ab3a..b5bad5e0b 100644
--- a/test/alterschema/alterschema_lint_draft7_test.cc
+++ b/test/alterschema/alterschema_lint_draft7_test.cc
@@ -2664,6 +2664,182 @@ TEST(AlterSchema_lint_draft7, orphan_definitions_1) {
   EXPECT_EQ(document, expected);
 }
 
+TEST(AlterSchema_lint_draft7, then_false_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": false,
+    "else": true
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": true,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": true,
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_4) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": false,
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_5) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "properties": {
+      "name": { "type": "string" }
+    },
+    "if": {
+      "properties": {
+        "name": { "type": "number" }
+      }
+    },
+    "then": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_6) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    },
+    "then": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "not": {
+      "properties": {
+        "flag": { "const": true }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_draft7, then_false_7) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  LINT_AND_FIX(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "if": {
+      "type": "object"
+    },
+    "then": false,
+    "else": false
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
 TEST(AlterSchema_lint_draft7, orphan_definitions_2) {
   sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
     "$schema": "http://json-schema.org/draft-07/schema#",