diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 637c8a0..4650a4e 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -6856,7 +6856,8 @@
 	/*
 	 * Sort the tags.
 	 */
-	sort_strings((char_u **)ga.ga_data, ga.ga_len);
+	if (ga.ga_data != NULL)
+	    sort_strings((char_u **)ga.ga_data, ga.ga_len);
 
 	/*
 	 * Check for duplicates.