diff --git a/mongoose.c b/mongoose.c
index b9c391e3..f6866e93 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -478,6 +478,7 @@ void cs_hmac_sha1(const unsigned char *key, size_t keylen,
 
 /* Amalgamated: #include "md5.h" */
 
+#ifndef CS_ENABLE_NATIVE_MD5
 static void byteReverse(unsigned char *buf, unsigned longs) {
 /* Forrest: MD5 expect LITTLE_ENDIAN, swap if BIG_ENDIAN */
 #if BYTE_ORDER == BIG_ENDIAN
@@ -661,6 +662,7 @@ void MD5_Final(unsigned char digest[16], MD5_CTX *ctx) {
   memcpy(digest, ctx->buf, 16);
   memset((char *) ctx, 0, sizeof(*ctx));
 }
+#endif  /* CS_ENABLE_NATIVE_MD5 */
 
 /*
  * Stringify binary data. Output buffer size must be 2 * size_of_input + 1