diff --git a/src/evalfunc.c b/src/evalfunc.c
index 12236f7..e670381 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -465,6 +465,21 @@
 }
 
 /*
+ * Check "type" is a list of 'any' or a blob or a string.
+ */
+    static int
+arg_string_list_or_blob(type_T *type, argcontext_T *context)
+{
+    if (type->tt_type == VAR_ANY
+		     || type->tt_type == VAR_LIST
+		     || type->tt_type == VAR_BLOB
+		     || type->tt_type == VAR_STRING)
+	return OK;
+    arg_type_mismatch(&t_list_any, type, context->arg_idx + 1);
+    return FAIL;
+}
+
+/*
  * Check "type" is a job.
  */
     static int
@@ -817,7 +832,7 @@
 static argcheck_T arg25_matchadd[] = {arg_string, arg_string, arg_number, arg_number, arg_dict_any};
 static argcheck_T arg25_matchaddpos[] = {arg_string, arg_list_any, arg_number, arg_number, arg_dict_any};
 static argcheck_T arg119_printf[] = {arg_string_or_nr, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};
-static argcheck_T arg23_reduce[] = {arg_list_or_blob, NULL, NULL};
+static argcheck_T arg23_reduce[] = {arg_string_list_or_blob, NULL, NULL};
 static argcheck_T arg24_remote_expr[] = {arg_string, arg_string, arg_string, arg_number};
 static argcheck_T arg23_remove[] = {arg_list_or_dict_or_blob, arg_remove2, arg_number};
 static argcheck_T arg2_repeat[] = {arg_repeat1, arg_number};