diff --git a/src/option.c b/src/option.c
index 8d950b1..bfe8f57 100644
--- a/src/option.c
+++ b/src/option.c
@@ -7210,7 +7210,7 @@
 	return FAIL;
 
     cb = get_callback(tv);
-    if (cb.cb_name == NULL)
+    if (cb.cb_name == NULL || *cb.cb_name == NUL)
     {
 	free_tv(tv);
 	return FAIL;