diff --git a/src/libsodium/sodium/utils.c b/src/libsodium/sodium/utils.c
index f13938c4..6666ef95 100644
--- a/src/libsodium/sodium/utils.c
+++ b/src/libsodium/sodium/utils.c
@@ -682,7 +682,7 @@ sodium_unpad(size_t *unpadded_buflen_p, const unsigned char *buf,
         is_barrier =
             (( (acc - 1U) & (pad_len - 1U) & ((c ^ 0x80) - 1U) ) >> 8) & 1U;
         acc |= c;
-        pad_len |= (i & - is_barrier);
+        pad_len |= i & (1U + ~is_barrier);
         valid |= (unsigned char) is_barrier;
     }
     *unpadded_buflen_p = padded_buflen - 1U - pad_len;