diff --git a/ctaocrypt/src/blake2b.c b/ctaocrypt/src/blake2b.c
index 7258efdeb..e43e8bdfa 100644
--- a/ctaocrypt/src/blake2b.c
+++ b/ctaocrypt/src/blake2b.c
@@ -324,7 +324,7 @@ int blake2b_update( blake2b_state *S, const byte *in, word64 inlen )
 
     if( inlen > fill )
     {
-      XMEMCPY( S->buf + left, in, fill ); /* Fill buffer */
+      XMEMCPY( S->buf + left, in, (word)fill ); /* Fill buffer */
       S->buflen += fill;
       blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
       blake2b_compress( S, S->buf ); /* Compress */
@@ -336,7 +336,7 @@ int blake2b_update( blake2b_state *S, const byte *in, word64 inlen )
     }
     else /* inlen <= fill */
     {
-      XMEMCPY( S->buf + left, in, inlen );
+      XMEMCPY( S->buf + left, in, (word)inlen );
       S->buflen += inlen; /* Be lazy, do not compress */
       in += inlen;
       inlen -= inlen;
@@ -357,12 +357,12 @@ int blake2b_final( blake2b_state *S, byte *out, byte outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    XMEMCPY( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    XMEMCPY( S->buf, S->buf + BLAKE2B_BLOCKBYTES, (word)S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );
   blake2b_set_lastblock( S );
-  XMEMSET( S->buf + S->buflen, 0, 2 * BLAKE2B_BLOCKBYTES - S->buflen );
+  XMEMSET( S->buf + S->buflen, 0, (word)(2 * BLAKE2B_BLOCKBYTES - S->buflen) );
          /* Padding */
   blake2b_compress( S, S->buf );