diff --git a/pkgs/applications/networking/browsers/firefox/builder.sh b/pkgs/applications/networking/browsers/firefox/builder.sh
index d53ff776a15..b025a71d425 100644
--- a/pkgs/applications/networking/browsers/firefox/builder.sh
+++ b/pkgs/applications/networking/browsers/firefox/builder.sh
@@ -13,22 +13,40 @@ ac_add_options --enable-strip
 ac_add_options --enable-default-toolkit=gtk2
 #ac_add_options --disable-shared
 #ac_add_options --enable-static
+#ac_add_options --with-system-jpeg
+#ac_add_options --with-system-png
+#ac_add_options --with-system-zlib
 EOF
 }
 
+postInstall=postInstall
+postInstall() {
+
+    # Strip some more stuff
+    strip -S $out/lib/*/* || true
+
+    # We don't need this (do we?)
+    rm -rf $out/include
+
+    # This fixes starting Firefox when there already is a running
+    # instance.  The `firefox' wrapper script actually expects to be
+    # in the same directory as `run-mozilla.sh', apparently.
+    cd $out/bin
+    mv firefox ../lib/firefox-*/
+    ln -s ../lib/firefox-*/firefox .
+
+    # Register extension etc.
+    echo "running firefox -register..."
+    (cd $out/lib/firefox-* && LD_LIBRARY_PATH=. ./firefox-bin -register) || false
+
+    echo "running regxpcom..."
+    (cd $out/lib/firefox-* && LD_LIBRARY_PATH=. ./regxpcom) || false
+    
+    echo "running regchrome..."
+    (cd $out/lib/firefox-* && LD_LIBRARY_PATH=. ./regchrome) || false
+    
+}
+
 makeFlags="-f client.mk build"
 
 genericBuild
-
-# Strip some more stuff
-strip -S $out/lib/*/* || true
-
-# We don't need this (do we?)
-rm -rf $out/include
-
-# This fixes starting Firefox when there already is a running
-# instance.  The `firefox' wrapper script actually expects to be in
-# the same directory as `run-mozilla.sh', apparently.
-cd $out/bin
-mv firefox ../lib/firefox-*/
-ln -s ../lib/firefox-*/firefox .
diff --git a/pkgs/applications/networking/browsers/firefox/default.nix b/pkgs/applications/networking/browsers/firefox/default.nix
index eafbf4e425d..f100b270f94 100644
--- a/pkgs/applications/networking/browsers/firefox/default.nix
+++ b/pkgs/applications/networking/browsers/firefox/default.nix
@@ -12,4 +12,6 @@ stdenv.mkDerivation {
   };
 
   buildInputs = [pkgconfig gtk perl zip libIDL libXi];
+
+  patches = [./writable-copies.patch];
 }
diff --git a/pkgs/applications/networking/browsers/firefox/writable-copies.patch b/pkgs/applications/networking/browsers/firefox/writable-copies.patch
new file mode 100644
index 00000000000..e3c7752c031
--- /dev/null
+++ b/pkgs/applications/networking/browsers/firefox/writable-copies.patch
@@ -0,0 +1,23 @@
+diff -rc mozilla-orig/xpcom/io/nsLocalFileUnix.cpp mozilla/xpcom/io/nsLocalFileUnix.cpp
+*** mozilla-orig/xpcom/io/nsLocalFileUnix.cpp	2004-04-03 01:48:18.000000000 +0200
+--- mozilla/xpcom/io/nsLocalFileUnix.cpp	2004-10-05 19:48:04.000000000 +0200
+***************
+*** 634,639 ****
+--- 634,640 ----
+          // get the dirs old permissions
+          if (NS_FAILED(rv = GetPermissions(&oldPerms)))
+              return rv;
++         oldPerms |= 0200;
+          if (NS_FAILED(rv = newParent->Create(DIRECTORY_TYPE, oldPerms)))
+              return rv;
+      } else {    // dir exists lets try to use leaf
+***************
+*** 758,763 ****
+--- 759,765 ----
+          // get the old permissions
+          PRUint32 myPerms;
+          GetPermissions(&myPerms);
++         myPerms |= 0200;
+  
+          // Create the new file with the old file's permissions, even if write
+          // permission is missing.  We can't create with write permission and