diff --git a/library/xtea.c b/library/xtea.c
index 5e479d2..f7df144 100644
--- a/library/xtea.c
+++ b/library/xtea.c
@@ -68,7 +68,7 @@
 /*
  * XTEA encrypt function
  */
-void xtea_crypt_ecb( xtea_context *ctx, int mode, unsigned char input[8],
+int xtea_crypt_ecb( xtea_context *ctx, int mode, unsigned char input[8],
                      unsigned char output[8])
 {
     uint32_t *k, v0, v1, i;
@@ -103,6 +103,8 @@
 
     PUT_ULONG_BE( v0, output, 0 );
     PUT_ULONG_BE( v1, output, 4 );
+
+    return( 0 );
 }
 
 #if defined(POLARSSL_SELF_TEST)