diff --git a/src/libsodium/include/sodium/crypto_secretstream_xchacha20poly1305.h b/src/libsodium/include/sodium/crypto_secretstream_xchacha20poly1305.h
index 7d3fa2a9..74a0c9b2 100644
--- a/src/libsodium/include/sodium/crypto_secretstream_xchacha20poly1305.h
+++ b/src/libsodium/include/sodium/crypto_secretstream_xchacha20poly1305.h
@@ -30,7 +30,8 @@ SODIUM_EXPORT
 size_t crypto_secretstream_xchacha20poly1305_keybytes(void);
 
 #define crypto_secretstream_xchacha20poly1305_MESSAGEBYTES_MAX \
-    SODIUM_MIN(SODIUM_SIZE_MAX, ((1ULL << 32) - 2ULL) * 64ULL)
+    SODIUM_MIN(SODIUM_SIZE_MAX - crypto_secretstream_xchacha20poly1305_ABYTES, \
+              (64ULL * (1ULL << 32) - 2ULL))
 SODIUM_EXPORT
 size_t crypto_secretstream_xchacha20poly1305_messagebytes_max(void);