diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 6387523a31530..3401628d742b6 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -195,7 +195,7 @@ static u32 gfs2_bitfit(const u8 *buffer, unsigned int buflen, u32 goal,
 	   depending on architecture.  I've experimented with several ways
 	   of writing this section such as using an else before the goto
 	   but this one seems to be the fastest. */
-	while ((unsigned char *)plong < end - 1) {
+	while ((unsigned char *)plong < end - sizeof(unsigned long)) {
 		prefetch(plong + 1);
 		if (((*plong) & LBITMASK) != lskipval)
 			break;