diff --git a/mkcramfs.c b/mkcramfs.c
index f9d12a2..a24e937 100644
--- a/mkcramfs.c
+++ b/mkcramfs.c
@@ -22,6 +22,7 @@
  * If you change the disk format of cramfs, please update fs/cramfs/README.
  */
 
+#define _GNU_SOURCE
 #include <sys/types.h>
 #include <sys/sysmacros.h>
 #include <stdio.h>
@@ -218,10 +219,9 @@ static void eliminate_doubles(struct entry *root, struct entry *orig) {
  * We define our own sorting function instead of using alphasort which
  * uses strcoll and changes ordering based on locale information.
  */
-static int cramsort (const void *a, const void *b)
+static int cramsort (const struct dirent **a, const struct dirent **b)
 {
-	return strcmp ((*(const struct dirent **) a)->d_name,
-		       (*(const struct dirent **) b)->d_name);
+	return strcmp ((*a)->d_name, (*b)->d_name);
 }
 
 static unsigned int parse_directory(struct entry *root_entry, const char *name, struct entry **prev, loff_t *fslen_ub)