diff -r ad7bbe9ea65b src/ex_cmds.c
--- a/src/ex_cmds.c	Tue Feb 26 22:54:11 2013 +0100
+++ b/src/ex_cmds.c	Mon Mar 04 12:35:41 2013 +0100
@@ -415,8 +415,15 @@
 	    }
 	    *s = NUL;
 	    /* Use last search pattern if sort pattern is empty. */
-	    if (s == p + 1 && last_search_pat() != NULL)
+	    if (s == p + 1)
+	    {
+		if (last_search_pat() == NULL)
+		{
+		    EMSG(_(e_noprevre));
+		    goto sortend;
+		}
 		regmatch.regprog = vim_regcomp(last_search_pat(), RE_MAGIC);
+	    }
 	    else
 		regmatch.regprog = vim_regcomp(p + 1, RE_MAGIC);
 	    if (regmatch.regprog == NULL)