diff --git a/mozilla/dom/src/base/nsGlobalWindow.h b/mozilla/dom/src/base/nsGlobalWindow.h
index a09495a6ad9..961fbf311b1 100644
--- a/mozilla/dom/src/base/nsGlobalWindow.h
+++ b/mozilla/dom/src/base/nsGlobalWindow.h
@@ -499,7 +499,10 @@ public:
   NS_DECL_NSIDOMNSLOCATION
 
 protected:
-  nsresult GetURI(nsIURI** aURL);
+  // In the case of jar: uris, we sometimes want the place the jar was
+  // fetched from as the URI instead of the jar: uri itself.  Pass in
+  // PR_TRUE for aGetInnermostURI when that's the case.
+  nsresult GetURI(nsIURI** aURL, PRBool aGetInnermostURI = PR_FALSE);
   nsresult GetWritableURI(nsIURI** aURL);
   nsresult SetURI(nsIURI* aURL);
   nsresult SetHrefWithBase(const nsAString& aHref, nsIURI* aBase,
diff --git a/mozilla/dom/src/base/nsLocation.cpp b/mozilla/dom/src/base/nsLocation.cpp
index c2d073d01f3..f6e32ffdc12 100644
--- a/mozilla/dom/src/base/nsLocation.cpp
+++ b/mozilla/dom/src/base/nsLocation.cpp
@@ -48,6 +48,7 @@
 #include "nsCDefaultURIFixup.h"
 #include "nsIURIFixup.h"
 #include "nsIURL.h"
+#include "nsIJARURI.h"
 #include "nsIIOService.h"
 #include "nsIServiceManager.h"
 #include "nsNetUtil.h"
@@ -256,7 +257,7 @@ LocationImpl::FindUsableBaseURI(nsIURI * aBaseURI, nsIDocShell * aParent, nsIURI
 
 
 nsresult
-LocationImpl::GetURI(nsIURI** aURI)
+LocationImpl::GetURI(nsIURI** aURI, PRBool aGetInnermostURI)
 {
   *aURI = nsnull;
 
@@ -277,6 +278,16 @@ LocationImpl::GetURI(nsIURI** aURI)
     return NS_OK;
   }
 
+  if (aGetInnermostURI) {
+    nsCOMPtr<nsIJARURI> jarURI(do_QueryInterface(uri));
+    while (jarURI) {
+      jarURI->GetJARFile(getter_AddRefs(uri));
+      jarURI = do_QueryInterface(uri);
+    }
+  }
+
+  NS_ASSERTION(uri, "nsJARURI screwed up?");
+
   nsCOMPtr<nsIURIFixup> urifixup(do_GetService(NS_URIFIXUP_CONTRACTID, &rv));
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -380,7 +391,7 @@ LocationImpl::GetHost(nsAString& aHost)
   nsCOMPtr<nsIURI> uri;
   nsresult result;
 
-  result = GetURI(getter_AddRefs(uri));
+  result = GetURI(getter_AddRefs(uri), PR_TRUE);
 
   if (uri) {
     nsCAutoString hostport;
@@ -419,7 +430,7 @@ LocationImpl::GetHostname(nsAString& aHostname)
   nsCOMPtr<nsIURI> uri;
   nsresult result;
 
-  result = GetURI(getter_AddRefs(uri));
+  result = GetURI(getter_AddRefs(uri), PR_TRUE);
 
   if (uri) {
     nsCAutoString host;
@@ -643,7 +654,7 @@ LocationImpl::GetPort(nsAString& aPort)
   nsCOMPtr<nsIURI> uri;
   nsresult result = NS_OK;
 
-  result = GetURI(getter_AddRefs(uri));
+  result = GetURI(getter_AddRefs(uri), PR_TRUE);
 
   if (uri) {
     PRInt32 port;