diff --git a/src/core/chunked_stream.js b/src/core/chunked_stream.js
index cf0e6b700..5eeb3f082 100644
--- a/src/core/chunked_stream.js
+++ b/src/core/chunked_stream.js
@@ -155,8 +155,15 @@ var ChunkedStream = (function ChunkedStreamClosure() {
       if (pos >= this.end) {
         return -1;
       }
-      this.ensureByte(pos);
-      return this.bytes[this.pos++];
+      var byte = this.bytes[pos];
+      if (byte === 0) {
+        // |byte| might be zero, because the corresponding chunk has not been
+        // loaded yet. In this case, this.ensureByte(pos) will throw an
+        // exception and nothing is returned.
+        this.ensureByte(pos);
+      }
+      this.pos++;
+      return byte;
     },
 
     getUint16: function ChunkedStream_getUint16() {