diff --git a/b64.cpp b/b64.cpp
index b926cad..bc8d898 100644
--- a/b64.cpp
+++ b/b64.cpp
@@ -66,5 +66,8 @@ int b64_encode(const unsigned char* aInput, int aInputLen, unsigned char* aOutpu
             b64_encode(&aInput[i*3], aInputLen % 3, &aOutput[i*4], aOutputLen - (i*4));
         }
     }
+
+    return ((aInputLen+2)/3)*4;
+
 }