diff --git a/modules/libjar/nsJARChannel.cpp b/modules/libjar/nsJARChannel.cpp
index 7828dd0267f9..47b61cc78a8b 100644
--- a/modules/libjar/nsJARChannel.cpp
+++ b/modules/libjar/nsJARChannel.cpp
@@ -672,7 +672,8 @@ nsJARChannel::Open(nsIInputStream **stream)
 
     // force load the jar file now so GetContentLength will return a
     // meaningful value once we return.
-    mJarInput->EnsureJarStream();
+    rv = mJarInput->EnsureJarStream();
+    if (NS_FAILED(rv)) return rv;
 
     NS_ADDREF(*stream = mJarInput);
     return NS_OK;
diff --git a/modules/libjar/test/unit/test_not_found.js b/modules/libjar/test/unit/test_not_found.js
new file mode 100644
index 000000000000..58fb2fe65121
--- /dev/null
+++ b/modules/libjar/test/unit/test_not_found.js
@@ -0,0 +1,18 @@
+// Should report file not found on non-existent files
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const path = "data/test_bug333423.zip";
+
+function run_test() {
+  var ios = Cc["@mozilla.org/network/io-service;1"].
+            getService(Ci.nsIIOService);
+  var spec = "jar:" + ios.newFileURI(do_get_file(path)).spec + "!/";
+  var channel = ios.newChannel(spec + "file_that_isnt_in.archive", null, null);
+  try {
+    instr = channel.open();
+    do_throw("Failed to report that file doesn't exist")
+  } catch (e) {
+      do_check_true(e.name == "NS_ERROR_FILE_NOT_FOUND")
+  }
+}