diff --git a/src/typval.c b/src/typval.c
index e57d898..cd39a0d 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -527,6 +527,20 @@
 }
 
 /*
+ * Give an error and return FAIL unless "args[idx]" is a bool or a number.
+ */
+    int
+check_for_bool_or_number_arg(typval_T *args, int idx)
+{
+    if (args[idx].v_type != VAR_BOOL && args[idx].v_type != VAR_NUMBER)
+    {
+	semsg(_(e_bool_or_number_required_for_argument_nr), idx + 1);
+	return FAIL;
+    }
+    return OK;
+}
+
+/*
  * Check for an optional bool argument at 'idx'.
  * Return FAIL if the type is wrong.
  */
@@ -539,6 +553,18 @@
 }
 
 /*
+ * Check for an optional bool or number argument at 'idx'.
+ * Return FAIL if the type is wrong.
+ */
+    int
+check_for_opt_bool_or_number_arg(typval_T *args, int idx)
+{
+    if (args[idx].v_type == VAR_UNKNOWN)
+	return OK;
+    return check_for_bool_or_number_arg(args, idx);
+}
+
+/*
  * Give an error and return FAIL unless "args[idx]" is a blob.
  */
     int