diff --git a/lib/csharp/src/Protocol/TJSONProtocol.cs b/lib/csharp/src/Protocol/TJSONProtocol.cs
index 2e8d99f..4081d6e 100644
--- a/lib/csharp/src/Protocol/TJSONProtocol.cs
+++ b/lib/csharp/src/Protocol/TJSONProtocol.cs
@@ -544,6 +544,11 @@
             int len = b.Length;
             int off = 0;
 
+            // Ignore padding
+            int bound = len >= 2 ? len - 2 : 0;
+            for (int i = len - 1; i >= bound && b[i] == '='; --i) {
+                --len;
+            }
             while (len >= 3)
             {
                 // Encode 3 bytes at a time