diff --git a/ctaocrypt/src/hmac.c b/ctaocrypt/src/hmac.c
index 80867eb65..6c1a2d052 100644
--- a/ctaocrypt/src/hmac.c
+++ b/ctaocrypt/src/hmac.c
@@ -30,7 +30,7 @@
 static int InitHmac(Hmac* hmac, int type)
 {
     hmac->innerHashKeyed = 0;
-    hmac->macType = type;
+    hmac->macType = (byte)type;
 
     if (!(type == MD5 || type == SHA || type == SHA256))
         return BAD_FUNC_ARG;