diff --git a/src/aead.c b/src/aead.c
index d23b37cd..eff13b21 100644
--- a/src/aead.c
+++ b/src/aead.c
@@ -53,7 +53,7 @@
 #endif
 
 #define CHUNK_SIZE_LEN          2
-#define CHUNK_SIZE_MASK         0X3FFF
+#define CHUNK_SIZE_MASK         0x3FFF
 
 /*
  * This is SIP004 proposed by @Mygod, the design of TCP chunk is from @breakwa11 and
@@ -489,7 +489,7 @@ aead_chunk_encrypt(cipher_ctx_t *ctx, uint8_t *p, uint8_t *c, uint8_t *n,
     int err;
     size_t clen;
     uint8_t len_buf[CHUNK_SIZE_LEN];
-    uint16_t t = htons((plen + tlen) & CHUNK_SIZE_MASK);
+    uint16_t t = htons(plen & CHUNK_SIZE_MASK);
     memcpy(len_buf, &t, CHUNK_SIZE_LEN);
 
     clen = CHUNK_SIZE_LEN + tlen;
@@ -586,18 +586,18 @@ aead_chunk_decrypt(cipher_ctx_t *ctx, uint8_t *p, uint8_t *c, uint8_t *n,
     mlen = ntohs(*(uint16_t *)len_buf);
     mlen = mlen & CHUNK_SIZE_MASK;
 
-    size_t chunk_len = tlen + CHUNK_SIZE_LEN + mlen;
+    size_t chunk_len = 2 * tlen + CHUNK_SIZE_LEN + mlen;
 
     if (*clen < chunk_len)
         return CRYPTO_NEED_MORE;
 
     sodium_increment(n, nlen);
 
-    err = cipher_aead_decrypt(ctx, p, plen, c + CHUNK_SIZE_LEN + tlen, mlen,
+    err = cipher_aead_decrypt(ctx, p, plen, c + CHUNK_SIZE_LEN + tlen, mlen + tlen,
                               NULL, 0, n, ctx->cipher->key, nlen, tlen);
     if (err)
         return CRYPTO_ERROR;
-    assert(*plen == mlen - tlen);
+    assert(*plen == mlen);
 
     sodium_increment(n, nlen);