diff --git a/crates/fmt/src/state/common.rs b/crates/fmt/src/state/common.rs
index 085916e60a98e..8ea7e6d914be2 100644
--- a/crates/fmt/src/state/common.rs
+++ b/crates/fmt/src/state/common.rs
@@ -588,7 +588,7 @@ impl<'ast> State<'_, 'ast> {
                                 self.s.offset(offset);
                             }
                         } else if style.is_isolated() {
-                            self.print_sep_unhandled(Separator::Space);
+                            self.print_sep_unhandled(Separator::Hardbreak);
                             self.s.offset(offset);
                         }
                     }
diff --git a/crates/fmt/src/state/mod.rs b/crates/fmt/src/state/mod.rs
index 878a19d882e99..15959173ad674 100644
--- a/crates/fmt/src/state/mod.rs
+++ b/crates/fmt/src/state/mod.rs
@@ -250,11 +250,17 @@ impl<'sess> State<'sess, '_> {
         self.has_crlf && self.char_at(self.cursor.pos) == Some('\r')
     }
 
+    /// Computes the space left, bounded by the max space left.
     fn space_left(&self) -> usize {
-        std::cmp::min(
-            self.s.space_left(),
-            self.config.line_length.saturating_sub(self.block_depth * self.config.tab_width),
-        )
+        std::cmp::min(self.s.space_left(), self.max_space_left(0))
+    }
+
+    /// Computes the maximum space left given the context information available:
+    /// `block_depth`, `tab_width`, and a user-defined unavailable size `prefix_len`.
+    fn max_space_left(&self, prefix_len: usize) -> usize {
+        self.config
+            .line_length
+            .saturating_sub(self.block_depth * self.config.tab_width + prefix_len)
     }
 
     fn break_offset_if_not_bol(&mut self, n: usize, off: isize, search: bool) {
diff --git a/crates/fmt/src/state/sol.rs b/crates/fmt/src/state/sol.rs
index 7303d6fb7d3d3..2728a3c85bdd3 100644
--- a/crates/fmt/src/state/sol.rs
+++ b/crates/fmt/src/state/sol.rs
@@ -1854,7 +1854,7 @@ impl<'ast> State<'_, 'ast> {
         _ = self.handle_span(self.cursor.span(span.lo()), false);
         if !self.handle_span(span.until(block.span), false) {
             self.cursor.advance_to(span.lo(), true);
-            self.print_word("assembly ");
+            self.print_word("assembly "); // 9 chars
             if let Some(dialect) = dialect {
                 self.print_ast_str_lit(dialect);
                 self.print_sep(Separator::Nbsp);
@@ -1871,7 +1871,7 @@ impl<'ast> State<'_, 'ast> {
                 self.print_sep(Separator::Nbsp);
             }
         }
-        self.print_yul_block(block, block.span, false);
+        self.print_yul_block(block, block.span, false, 9);
     }
 
     /// Prints a multiple-variable declaration with a single initializer expression,
diff --git a/crates/fmt/src/state/yul.rs b/crates/fmt/src/state/yul.rs
index 120d98312e0b2..0f973624bf9ec 100644
--- a/crates/fmt/src/state/yul.rs
+++ b/crates/fmt/src/state/yul.rs
@@ -26,11 +26,12 @@ impl<'ast> State<'_, 'ast> {
         }
 
         match kind {
-            yul::StmtKind::Block(stmts) => self.print_yul_block(stmts, span, false),
+            yul::StmtKind::Block(stmts) => self.print_yul_block(stmts, span, false, 0),
             yul::StmtKind::AssignSingle(path, expr) => {
                 self.print_path(path, false);
                 self.word(" := ");
                 self.neverbreak();
+                self.cursor.advance_to(expr.span.lo(), self.cursor.enabled);
                 self.print_yul_expr(expr);
             }
             yul::StmtKind::AssignMulti(paths, expr_call) => {
@@ -53,30 +54,30 @@ impl<'ast> State<'_, 'ast> {
             }
             yul::StmtKind::Expr(expr_call) => self.print_yul_expr(expr_call),
             yul::StmtKind::If(expr, stmts) => {
-                self.word("if ");
+                self.print_word("if "); // 3 chars
                 self.print_yul_expr(expr);
-                self.nbsp();
-                self.print_yul_block(stmts, span, false);
+                self.nbsp(); // 1 char
+                self.print_yul_block(stmts, span, false, 4 + self.estimate_size(expr.span));
             }
             yul::StmtKind::For(yul::StmtFor { init, cond, step, body }) => {
                 self.ibox(0);
 
-                self.word("for ");
-                self.print_yul_block(init, init.span, false);
+                self.print_word("for "); // 4 chars
+                self.print_yul_block(init, init.span, false, 4);
 
                 self.space();
                 self.print_yul_expr(cond);
 
                 self.space();
-                self.print_yul_block(step, step.span, false);
+                self.print_yul_block(step, step.span, false, 0);
 
                 self.space();
-                self.print_yul_block(body, body.span, false);
+                self.print_yul_block(body, body.span, false, 0);
 
                 self.end();
             }
             yul::StmtKind::Switch(yul::StmtSwitch { selector, cases }) => {
-                self.word("switch ");
+                self.print_word("switch ");
                 self.print_yul_expr(selector);
 
                 self.print_trailing_comment(selector.span.hi(), None);
@@ -88,7 +89,7 @@ impl<'ast> State<'_, 'ast> {
                             constant.span.lo(),
                             CommentConfig::default().mixed_prev_space(),
                         );
-                        self.word("case ");
+                        self.print_word("case ");
                         self.print_lit_yul(constant);
                         self.nbsp();
                     } else {
@@ -96,16 +97,16 @@ impl<'ast> State<'_, 'ast> {
                             body.span.lo(),
                             CommentConfig::default().mixed_prev_space(),
                         );
-                        self.word("default ");
+                        self.print_word("default ");
                     }
-                    self.print_yul_block(body, *span, false);
+                    self.print_yul_block(body, *span, false, 0);
 
                     self.print_trailing_comment(selector.span.hi(), None);
                 }
             }
-            yul::StmtKind::Leave => self.word("leave"),
-            yul::StmtKind::Break => self.word("break"),
-            yul::StmtKind::Continue => self.word("continue"),
+            yul::StmtKind::Leave => self.print_word("leave"),
+            yul::StmtKind::Break => self.print_word("break"),
+            yul::StmtKind::Continue => self.print_word("continue"),
             yul::StmtKind::FunctionDef(func) => {
                 let yul::Function { name, parameters, returns, body } = func;
                 let params_hi = parameters
@@ -116,7 +117,7 @@ impl<'ast> State<'_, 'ast> {
 
                 self.cbox(0);
                 self.s.ibox(0);
-                self.word("function ");
+                self.print_word("function ");
                 self.print_ident(name);
                 self.print_tuple(
                     parameters,
@@ -143,12 +144,12 @@ impl<'ast> State<'_, 'ast> {
                     );
                 }
                 self.end();
-                self.print_yul_block(body, span, skip_opening_brace);
+                self.print_yul_block(body, span, skip_opening_brace, 0);
                 self.end();
             }
             yul::StmtKind::VarDecl(idents, expr) => {
                 self.s.ibox(self.ind);
-                self.word("let ");
+                self.print_word("let ");
                 self.commasep(
                     idents,
                     stmt.span.lo(),
@@ -158,7 +159,7 @@ impl<'ast> State<'_, 'ast> {
                     ListFormat::consistent(),
                 );
                 if let Some(expr) = expr {
-                    self.word(" :=");
+                    self.print_word(" :=");
                     self.space();
                     self.print_yul_expr(expr);
                 }
@@ -201,6 +202,7 @@ impl<'ast> State<'_, 'ast> {
         block: &'ast yul::Block<'ast>,
         span: Span,
         skip_opening_brace: bool,
+        prefix_len: usize,
     ) {
         if self.handle_span(span, false) {
             return;
@@ -210,9 +212,15 @@ impl<'ast> State<'_, 'ast> {
             self.print_word("{");
         }
 
-        let can_inline_block = block.len() <= 1
-            && !self.is_multiline_yul_block(block)
-            && self.estimate_size(block.span) <= self.space_left();
+        let can_inline_block = if block.len() <= 1 && !self.is_multiline_yul_block(block) {
+            if self.max_space_left(prefix_len) == 0 {
+                self.estimate_size(block.span) + self.config.tab_width < self.space_left()
+            } else {
+                self.estimate_size(block.span) + prefix_len < self.space_left()
+            }
+        } else {
+            false
+        };
         if can_inline_block {
             self.neverbreak();
             self.print_block_inner(
diff --git a/crates/fmt/testdata/Yul/fmt.sol b/crates/fmt/testdata/Yul/fmt.sol
index 3db955e48ea69..26ae8f2eb884d 100644
--- a/crates/fmt/testdata/Yul/fmt.sol
+++ b/crates/fmt/testdata/Yul/fmt.sol
@@ -228,7 +228,28 @@ contract Yul {
                     result, p := parseValue(input, 0, p, e)
                     mstore8(e, c) // Restore the original char at the end.
                 }
-                if or(lt(p, e), iszero(result)) { fail() }
+            }
+        }
+
+        assembly {
+            function parseNumber(s_, packed_, pIn_, end_) -> _item, _pOut {
+                _pOut := pIn_
+                if eq(chr(_pOut), 45) { _pOut := add(_pOut, 1) } // '-'.
+                if iszero(lt(sub(chr(_pOut), 48), 10)) { fail() } // Not '0'..'9'.
+                let c_ := chr(_pOut)
+                _pOut := add(_pOut, 1)
+                if iszero(eq(c_, 48)) {
+                    _pOut := skip0To9s(_pOut, end_, 0)
+                } // Not '0'.
+                if eq(chr(_pOut), 46) {
+                    _pOut := skip0To9s(add(_pOut, 1), end_, 1)
+                } // '.'.
+                let t_ := mload(_pOut)
+                if eq(or(0x20, byte(0, t_)), 101) {
+                    // forgefmt: disable-next-item
+                    _pOut := skip0To9s(add(byte(sub(byte(1, t_), 14), 0x010001), // '+', '-'.
+                        add(_pOut, 1)), end_, 1)
+                }
             }
         }
     }
diff --git a/crates/fmt/testdata/Yul/original.sol b/crates/fmt/testdata/Yul/original.sol
index 11347d492e911..1fba402759726 100644
--- a/crates/fmt/testdata/Yul/original.sol
+++ b/crates/fmt/testdata/Yul/original.sol
@@ -171,7 +171,24 @@ contract Yul {
                     result, p := parseValue(input, 0, p, e)
                     mstore8(e, c) // Restore the original char at the end.
                 }
-                if or(lt(p, e), iszero(result)) { fail() }
+            }
+        }
+
+        assembly {
+            function parseNumber(s_, packed_, pIn_, end_) -> _item, _pOut {
+                _pOut := pIn_
+                if eq(chr(_pOut), 45) { _pOut := add(_pOut, 1) } // '-'.
+                if iszero(lt(sub(chr(_pOut), 48), 10)) { fail() } // Not '0'..'9'.
+                let c_ := chr(_pOut)
+                _pOut := add(_pOut, 1)
+                if iszero(eq(c_, 48)) { _pOut := skip0To9s(_pOut, end_, 0) } // Not '0'.
+                if eq(chr(_pOut), 46) { _pOut := skip0To9s(add(_pOut, 1), end_, 1) } // '.'.
+                let t_ := mload(_pOut)
+                if eq(or(0x20, byte(0, t_)), 101) {
+                    // forgefmt: disable-next-item
+                    _pOut := skip0To9s(add(byte(sub(byte(1, t_), 14), 0x010001), // '+', '-'.
+                        add(_pOut, 1)), end_, 1)
+                }
             }
         }
     }