diff --git a/blink/internal/fixer/rules/method_argument_space.go b/blink/internal/fixer/rules/method_argument_space.go
index 023e9c5678..6b309bf28f 100644
--- a/blink/internal/fixer/rules/method_argument_space.go
+++ b/blink/internal/fixer/rules/method_argument_space.go
@@ -710,6 +710,25 @@ func argListIsMultiline(s *tokens.Stream, open, closeIdx int) bool {
 
 // isCallOrDeclParen reports whether the "(" at open opens a function/method call
 // or a function/closure declaration (not a control structure, array or grouping).
+// isLanguageConstructBareword reports whether the identifier at p is a language
+// construct (eval, exit, die) used as a bareword rather than a member call. PHP
+// tokenizes these as their own constructs, not T_STRING, so MethodArgumentSpace
+// never reflows their parentheses as a function argument list.
+func isLanguageConstructBareword(s *tokens.Stream, p int) bool {
+	switch strings.ToLower(s.At(p).Value) {
+	case "eval", "exit", "die":
+	default:
+		return false
+	}
+	if pp := sigPrev(s, p); pp >= 0 && s.At(pp).Kind == token.Punct {
+		switch s.At(pp).Value {
+		case "->", "?->", "::":
+			return false // "$obj->eval(...)" is a real method call
+		}
+	}
+	return true
+}
+
 func isCallOrDeclParen(s *tokens.Stream, open int) bool {
 	p := sigPrev(s, open)
 	if p < 0 {
@@ -718,6 +737,9 @@ func isCallOrDeclParen(s *tokens.Stream, open int) bool {
 	t := s.At(p)
 	switch t.Kind {
 	case token.Ident, token.Variable:
+		if t.Kind == token.Ident && isLanguageConstructBareword(s, p) {
+			return false // eval()/exit()/die() are language constructs, not function calls
+		}
 		return true
 	case token.Punct:
 		// ")" and "]" end a prior call/subscript; "}" ends a dynamic name like
diff --git a/blink/internal/fixer/rules/method_argument_space_test.go b/blink/internal/fixer/rules/method_argument_space_test.go
index ac811d36fc..017c156b89 100644
--- a/blink/internal/fixer/rules/method_argument_space_test.go
+++ b/blink/internal/fixer/rules/method_argument_space_test.go
@@ -54,3 +54,19 @@ func TestMethodArgumentSpaceSourceURL(t *testing.T) {
 		t.Fatalf("SourceURL mismatch: derived=%q declared=%q", got, r.SourceURL())
 	}
 }
+
+// A single-argument call to the eval/exit/die language constructs is not a
+// function call, so a heredoc argument must not be reflowed onto its own line.
+func TestMethodArgumentSpaceEvalHeredocNotReflowed(t *testing.T) {
+	t.Parallel()
+	src := "<?php\neval(<<<EOPHP\nnamespace X;\nEOPHP\n);\n"
+	if got, changed := apply(t, MethodArgumentSpace{}, src); changed || got != src {
+		t.Fatalf("eval heredoc must be left inline; changed=%v got=%q", changed, got)
+	}
+	// a real method named eval is still a call: its heredoc arg reflows onto its own line
+	call := "<?php\n$o->eval(<<<EOT\nbody\nEOT\n);\n"
+	want := "<?php\n$o->eval(\n    <<<EOT\nbody\nEOT\n);\n"
+	if got, changed := apply(t, MethodArgumentSpace{}, call); !changed || got != want {
+		t.Fatalf("a real ->eval() method call must still be processed; changed=%v got=%q", changed, got)
+	}
+}
diff --git a/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/expected.php b/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/expected.php
new file mode 100644
index 0000000000..86559cdc58
--- /dev/null
+++ b/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/expected.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace App;
+
+class Loader
+{
+    public function load(string $ns): void
+    {
+        eval(<<<EOPHP
+namespace {$ns};
+
+function loaded(): bool
+{
+    return true;
+}
+EOPHP
+        );
+    }
+}
diff --git a/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/input.php b/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/input.php
new file mode 100644
index 0000000000..86559cdc58
--- /dev/null
+++ b/blink/internal/parityfixture/testdata/cases/eval_heredoc_single_arg/input.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace App;
+
+class Loader
+{
+    public function load(string $ns): void
+    {
+        eval(<<<EOPHP
+namespace {$ns};
+
+function loaded(): bool
+{
+    return true;
+}
+EOPHP
+        );
+    }
+}