diff --git a/library/md5.c b/library/md5.c
index 9c5d73a..b68bd4b 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -580,7 +580,7 @@
 
         if( i == 5 || i == 6 )
         {
-            memset( buf, '\xAA', buflen = 80 );
+            memset( buf, 0xAA, buflen = 80 );
             md5_hmac_starts( &ctx, buf, buflen );
         }
         else