diff --git a/src/eval.c b/src/eval.c
index 785d841..444c0fa 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3428,8 +3428,12 @@
 			ufunc_T *ufunc = rettv->vval.v_partial->pt_func;
 
 			// compile it here to get the return type
-			compile_def_function(ufunc,
-						 TRUE, PROFILING(ufunc), NULL);
+			if (compile_def_function(ufunc,
+					 TRUE, PROFILING(ufunc), NULL) == FAIL)
+			{
+			    clear_tv(rettv);
+			    ret = FAIL;
+			}
 		    }
 		}
 		if (ret == NOTDONE)
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 4c63217..392a091 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -1118,6 +1118,11 @@
       Ref = (j) => !j
   END
   CheckDefAndScriptFailure(lines, 'E1012: Type mismatch; expected func(number) but got func(any): bool')
+
+  lines =<< trim END
+      echo filter([1, 2, 3], (_, v: string) => v + 1) 
+  END
+  CheckDefAndScriptFailure(lines, 'E1051:')
 enddef
 
 def Test_heredoc()
diff --git a/src/version.c b/src/version.c
index 0fb8896..4c0fb5c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2528,
+/**/
     2527,
 /**/
     2526,