diff --git a/lib/java/src/org/apache/thrift/protocol/TJSONProtocol.java b/lib/java/src/org/apache/thrift/protocol/TJSONProtocol.java
index 10af5c7..f07a4a7 100644
--- a/lib/java/src/org/apache/thrift/protocol/TJSONProtocol.java
+++ b/lib/java/src/org/apache/thrift/protocol/TJSONProtocol.java
@@ -331,7 +331,7 @@
       return (byte)((char)ch - '0');
     }
     else if ((ch >= 'a') && (ch <= 'f')) {
-      return (byte)((char)ch - 'a');
+      return (byte)((char)ch - 'a' + 10);
     }
     else {
       throw new TProtocolException(TProtocolException.INVALID_DATA,
@@ -346,7 +346,7 @@
       return (byte)((char)val + '0');
     }
     else {
-      return (byte)((char)val + 'a');
+      return (byte)((char)(val - 10) + 'a');
     }
   }