diff --git a/src/libsodium/crypto_generichash/blake2/ref/blake2b-ref.c b/src/libsodium/crypto_generichash/blake2/ref/blake2b-ref.c
index bd7bc0b8..b07ad228 100644
--- a/src/libsodium/crypto_generichash/blake2/ref/blake2b-ref.c
+++ b/src/libsodium/crypto_generichash/blake2/ref/blake2b-ref.c
@@ -395,7 +395,7 @@ int blake2b_final( blake2b_state *S, uint8_t *out, uint8_t outlen )
     blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
     blake2b_compress( S, S->buf );
     S->buflen -= BLAKE2B_BLOCKBYTES;
-    memcpy( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
+    memmove( S->buf, S->buf + BLAKE2B_BLOCKBYTES, S->buflen );
   }
 
   blake2b_increment_counter( S, S->buflen );