diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index de09baa..301a55c 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -1005,6 +1005,20 @@
       Foo()
   END
   CheckScriptSuccess(lines)
+
+  lines =<< trim END
+      vim9script
+      def g:TestFunc(f: func())
+      enddef
+      legacy call g:TestFunc({-> 0})
+      delfunc g:TestFunc
+
+      def g:TestFunc(f: func(number))
+      enddef
+      legacy call g:TestFunc({nr -> 0})
+      delfunc g:TestFunc
+  END
+  CheckScriptSuccess(lines)
 enddef
 
 " Default arg and varargs
diff --git a/src/version.c b/src/version.c
index 5502952..653e578 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3035,
+/**/
     3034,
 /**/
     3033,
diff --git a/src/vim9type.c b/src/vim9type.c
index f3718e4..91dc3fe 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -171,7 +171,7 @@
     if (type == NULL)
 	return &t_any;
     type->tt_type = VAR_FUNC;
-    type->tt_member = ret_type;
+    type->tt_member = ret_type == NULL ? &t_unknown : ret_type;
     type->tt_argcount = argcount;
     type->tt_args = NULL;
     return type;
@@ -188,7 +188,7 @@
     // recognize commonly used types
     if (argcount <= 0)
     {
-	if (ret_type == &t_unknown)
+	if (ret_type == &t_unknown || ret_type == NULL)
 	{
 	    // (argcount == 0) is not possible
 	    return &t_func_unknown;