diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index c7135a3..d6bd0eb 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -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)
diff --git a/src/version.c b/src/version.c
index b4234e0..97fdd99 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    851,
+/**/
     850,
 /**/
     849,