diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 20ad3ba..251790b 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -554,6 +554,18 @@
       echo Ref(1, 'x')
   END
   CheckDefFailure(lines, 'E1013: Argument 2: type mismatch, expected number but got string')
+
+  lines =<< trim END
+    var Ref: func(job, string, number)
+    Ref = (x, y) => 0
+  END
+  CheckDefAndScriptFailure(lines, 'E1012:')
+
+  lines =<< trim END
+    var Ref: func(job, string)
+    Ref = (x, y, z) => 0
+  END
+  CheckDefAndScriptFailure(lines, 'E1012:')
 enddef
 
 def Test_lambda_uses_assigned_var()