diff --git a/common/stringbucket.c b/common/stringbucket.c
line changes: +1/-1
index 27c1023..7fd0bfa
--- a/common/stringbucket.c
+++ b/common/stringbucket.c

@@ -40,7 +40,7 @@ struct stringbucket * stringbucket_open(const char *filename) {
 	flock(obj->fd, LOCK_UN);
 	obj->size = st.st_size;
 	obj->list = mmap(NULL, obj->size, PROT_READ | PROT_WRITE, MAP_SHARED, obj->fd, 0);
-	if (obj->list == NULL) {
+	if (obj->list == MAP_FAILED) {
 		perror("stringbucket mmap");
 		close(obj->fd);
 		free(obj);