diff --git a/lib/src/ssl_funcs/Md5.cc b/lib/src/ssl_funcs/Md5.cc
index 411d7ef4..318a9c82 100644
--- a/lib/src/ssl_funcs/Md5.cc
+++ b/lib/src/ssl_funcs/Md5.cc
@@ -51,7 +51,7 @@ uint32_t Md5Encode::fillData(const char *inDataPtr,
     // int grop_num = bitNum / BIT_OF_GROUP;
     int modBitNum = bitNum % BIT_OF_GROUP;
     int bitNeedFill = 0;
-    if (modBitNum > (BIT_OF_GROUP - SRC_DATA_LEN))
+    if (modBitNum >= (BIT_OF_GROUP - SRC_DATA_LEN))
     {
         bitNeedFill = (BIT_OF_GROUP - modBitNum);
         bitNeedFill += (BIT_OF_GROUP - SRC_DATA_LEN);
diff --git a/lib/tests/unittests/MD5Test.cc b/lib/tests/unittests/MD5Test.cc
index 5545ae71..8340be2b 100644
--- a/lib/tests/unittests/MD5Test.cc
+++ b/lib/tests/unittests/MD5Test.cc
@@ -9,4 +9,8 @@ DROGON_TEST(Md5Test)
                                 "1234567890") ==
           "49CB3608E2B33FAD6B65DF8CB8F49668");
     CHECK(drogon::utils::getMd5("1") == "C4CA4238A0B923820DCC509A6F75849B");
+    CHECK(drogon::utils::getMd5("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+                                "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+                                "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF") ==
+          "59F761506DFA597B0FAF1968F7CCA867");
 }