diff --git a/libcomposefs/lcfs-utils.h b/libcomposefs/lcfs-utils.h
index 4f18bd3..c7f6c76 100644
--- a/libcomposefs/lcfs-utils.h
+++ b/libcomposefs/lcfs-utils.h
@@ -161,4 +161,10 @@ static inline void *steal_pointer(void *pp)
 /* type safety */
 #define steal_pointer(pp) (0 ? (*(pp)) : (steal_pointer)(pp))
 
+static inline const char *gnu_basename(const char *filename)
+{
+	const char *p = strrchr(filename, '/');
+	return p ? p + 1 : filename;
+}
+
 #endif
diff --git a/tools/mkcomposefs.c b/tools/mkcomposefs.c
index a5074e3..238439b 100644
--- a/tools/mkcomposefs.c
+++ b/tools/mkcomposefs.c
@@ -945,7 +945,7 @@ static void digest_to_string(const uint8_t *csum, char *buf)
 
 static void usage(const char *argv0)
 {
-	const char *bin = basename(argv0);
+	const char *bin = gnu_basename(argv0);
 	fprintf(stderr,
 		"Usage: %s [OPTIONS] SOURCE IMAGE\n"
 		"Options:\n"
diff --git a/tools/mountcomposefs.c b/tools/mountcomposefs.c
index 1e01b4f..3dc6835 100644
--- a/tools/mountcomposefs.c
+++ b/tools/mountcomposefs.c
@@ -37,10 +37,11 @@
 #include <linux/fsverity.h>
 
 #include "libcomposefs/lcfs-mount.h"
+#include "libcomposefs/lcfs-utils.h"
 
 static void usage(const char *argv0)
 {
-	const char *bin = basename(argv0);
+	const char *bin = gnu_basename(argv0);
 	fprintf(stderr,
 		"usage: %s [-t type] [-o opt[,opts..]] IMAGE MOUNTPOINT\n"
 		"Example:\n"