diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index 5024f4a..8433ef8 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -82,7 +82,8 @@
 
 int main( int argc, char *argv[] )
 {
-    int ret = 1, i, n;
+    int ret = 1, i;
+    unsigned n;
     int exit_code = MBEDTLS_EXIT_FAILURE;
     int mode;
     size_t keylen, ilen, olen;