diff --git a/mozilla/docshell/test/Makefile.in b/mozilla/docshell/test/Makefile.in
index 384aec1112a..2078525a546 100644
--- a/mozilla/docshell/test/Makefile.in
+++ b/mozilla/docshell/test/Makefile.in
@@ -59,6 +59,7 @@ _TEST_FILES = \
 		test_bug344861.html \
 		test_bug369814.html \
 		bug369814.zip       \
+		bug369814.jar       \
 		test_bug384014.html \
 		test_bug387979.html \
 		test_bug404548.html \
diff --git a/mozilla/docshell/test/test_bug369814.html b/mozilla/docshell/test/test_bug369814.html
index 85a7b3bdb7a..7944b950488 100644
--- a/mozilla/docshell/test/test_bug369814.html
+++ b/mozilla/docshell/test/test_bug369814.html
@@ -149,6 +149,18 @@ var gTests = [
     "pokes" : { },
     "func" : anchorTest,
   },
+  { "name" : "iframes.html loaded from view-source jar type, pref disabled",
+    "url" : "jar:view-source:http://localhost:8888/tests/docshell/test/bug369814.jar!/iframes.html",
+    "pref" : true,
+    "pokes" : { },
+    "func" : loadErrorTest
+  },
+  { "name" : "iframes.html loaded from view-source jar type, pref enabled",
+    "url" : "jar:view-source:http://localhost:8888/tests/docshell/test/bug369814.jar!/iframes.html",
+    "pref" : true,
+    "pokes" : { },
+    "func" : loadErrorTest
+  },
 ];
 
 var gNextTest = 0;
diff --git a/mozilla/modules/libjar/nsJARChannel.cpp b/mozilla/modules/libjar/nsJARChannel.cpp
index 088dd8e91b0..a09d1bee4a1 100644
--- a/mozilla/modules/libjar/nsJARChannel.cpp
+++ b/mozilla/modules/libjar/nsJARChannel.cpp
@@ -46,6 +46,7 @@
 #include "nsEscape.h"
 #include "nsIPrefService.h"
 #include "nsIPrefBranch.h"
+#include "nsIViewSourceChannel.h"
 #include "nsChannelProperties.h"
 
 #include "nsIScriptSecurityManager.h"
@@ -775,8 +776,11 @@ nsJARChannel::OnDownloadComplete(nsIDownloader *downloader,
             nsCAutoString contentType;
             nsCAutoString charset;
             NS_ParseContentType(header, contentType, charset);
-            mIsUnsafe = !contentType.EqualsLiteral("application/java-archive") &&
-                        !contentType.EqualsLiteral("application/x-jar");
+            nsCAutoString channelContentType;
+            channel->GetContentType(channelContentType);
+            mIsUnsafe = !(contentType.Equals(channelContentType) &&
+                          (contentType.EqualsLiteral("application/java-archive") ||
+                           contentType.EqualsLiteral("application/x-jar")));
             rv = httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("Content-Disposition"),
                                                 header);
             if (NS_SUCCEEDED(rv))
@@ -809,6 +813,14 @@ nsJARChannel::OnDownloadComplete(nsIDownloader *downloader,
         }
     }
 
+    if (NS_SUCCEEDED(status)) {
+        // Refuse to unpack view-source: jars even if open-unsafe-types is set.
+        nsCOMPtr<nsIViewSourceChannel> viewSource = do_QueryInterface(channel);
+        if (viewSource) {
+            status = NS_ERROR_UNSAFE_CONTENT_TYPE;
+        }
+    }
+
     if (NS_SUCCEEDED(status)) {
         mJarFile = file;