diff --git a/src/core/chunked_stream.js b/src/core/chunked_stream.js
index f82b48f69..13a33096d 100644
--- a/src/core/chunked_stream.js
+++ b/src/core/chunked_stream.js
@@ -271,8 +271,6 @@ var ChunkedStream = (function ChunkedStreamClosure() {
       subStream.dict = dict;
       return subStream;
     },
-
-    isStream: true
   };
 
   return ChunkedStream;
diff --git a/src/core/stream.js b/src/core/stream.js
index a7da21c1e..6f1e58c16 100644
--- a/src/core/stream.js
+++ b/src/core/stream.js
@@ -129,7 +129,6 @@ var Stream = (function StreamClosure() {
     makeSubStream: function Stream_makeSubStream(start, length, dict) {
       return new Stream(this.bytes.buffer, start, length, dict);
     },
-    isStream: true
   };
 
   return Stream;