diff --git a/SocketIO-iOSTests/SocketTestCases.swift b/SocketIO-iOSTests/SocketTestCases.swift
index b090e7d..da5277c 100644
--- a/SocketIO-iOSTests/SocketTestCases.swift
+++ b/SocketIO-iOSTests/SocketTestCases.swift
@@ -111,6 +111,8 @@ class SocketTestCases: NSObject {
     
     static func testJSONWithBuffer(abstractSocketSend:SocketSendFunction) {
         let testName = "testJSONWithBuffer"
+        let data = "0".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
+        
         func didGetResult(result:NSArray?, ack:AckEmitter?) {
             if let json = result?.firstObject as? NSDictionary {
                 XCTAssertEqual((json.valueForKey("testString")! as! String), "test")
@@ -123,7 +125,7 @@ class SocketTestCases: NSObject {
                 XCTFail("Should have NSDictionary as result")
             }
         }
-        let json = ["name": "test", "testArray": ["hallo"], "nestedTest": ["test": "test"], "number": 15]
+        let json = ["name": "test", "testArray": ["hallo"], "nestedTest": ["test": "test"], "number": 15, "buf": data]
         
         abstractSocketSend(testName: testName, emitData: json, callback: didGetResult)
     }
diff --git a/SocketIOClientSwift/SocketPacket.swift b/SocketIOClientSwift/SocketPacket.swift
index ee648fc..3f65d4a 100644
--- a/SocketIOClientSwift/SocketPacket.swift
+++ b/SocketIOClientSwift/SocketPacket.swift
@@ -281,12 +281,14 @@ private extension SocketPacket {
             }
             
             return arr
-        } else if let dict = data as? NSMutableDictionary {
+        } else if let dict = data as? NSDictionary {
+            let mutDict = NSMutableDictionary(dictionary: dict)
+            
             for (key, value) in dict {
-                dict[key as! NSCopying] = shred(value, binary: &binary)
+                mutDict[key as! NSCopying] = shred(value, binary: &binary)
             }
             
-            return dict
+            return mutDict
         } else {
             return data
         }