diff --git a/src/cmd/compile/internal/types2/builtins.go b/src/cmd/compile/internal/types2/builtins.go
index 43da6a1529..bd1ea0fdc1 100644
--- a/src/cmd/compile/internal/types2/builtins.go
+++ b/src/cmd/compile/internal/types2/builtins.go
@@ -368,8 +368,8 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			return
 		}
 
-		if !x.assignableTo(check, m.key, nil) {
-			check.invalidArgf(x, "%s is not assignable to %s", x, m.key)
+		check.assignment(x, m.key, "argument to delete")
+		if x.mode == invalid {
 			return
 		}
 
diff --git a/src/cmd/compile/internal/types2/testdata/builtins.src b/src/cmd/compile/internal/types2/testdata/builtins.src
index 69cc48798e..e473bd1df2 100644
--- a/src/cmd/compile/internal/types2/testdata/builtins.src
+++ b/src/cmd/compile/internal/types2/testdata/builtins.src
@@ -283,7 +283,7 @@ func delete1() {
 	delete() // ERROR not enough arguments
 	delete(1) // ERROR not enough arguments
 	delete(1, 2, 3) // ERROR too many arguments
-	delete(m, 0 /* ERROR not assignable */)
+	delete(m, 0 /* ERROR cannot convert */)
 	delete(m, s)
 	_ = delete /* ERROR used as value */ (m, s)