diff --git a/browser/installer/package-manifest.in b/browser/installer/package-manifest.in
index 13c58000c65d..e513db71c54b 100644
--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -363,9 +363,7 @@
 @BINPATH@/@PREF_DIR@/firefox.js
 @BINPATH@/@PREF_DIR@/firefox-branding.js
 @BINPATH@/@PREF_DIR@/channel-prefs.js
-@BINPATH@/greprefs/all.js
-@BINPATH@/greprefs/security-prefs.js
-@BINPATH@/greprefs/xpinstall.js
+@BINPATH@/greprefs.js
 @BINPATH@/defaults/autoconfig/platform.js
 @BINPATH@/defaults/autoconfig/prefcalls.js
 
diff --git a/browser/installer/removed-files.in b/browser/installer/removed-files.in
index 125b30f4ac33..82be8463764c 100644
--- a/browser/installer/removed-files.in
+++ b/browser/installer/removed-files.in
@@ -780,6 +780,9 @@ components/xuldoc.xpt
 components/xultmpl.xpt
 components/zipwriter.xpt
 components/firefox.xpt
+greprefs/all.js
+greprefs/security-prefs.js
+greprefs/xpinstall.js
 run-mozilla.sh
 firefox
 dependentlibs.list
@@ -810,4 +813,4 @@ install.rdf
 @DLL_PREFIX@jsj@DLL_SUFFIX@
 #ifdef XP_WIN
 components/brwsrcmp.dll
-#endif
\ No newline at end of file
+#endif
diff --git a/modules/libpref/src/Makefile.in b/modules/libpref/src/Makefile.in
index 450c9fd40425..b7836f0385ea 100644
--- a/modules/libpref/src/Makefile.in
+++ b/modules/libpref/src/Makefile.in
@@ -72,8 +72,6 @@ ifdef WINCE
 DEFINES += -DWINCE=1
 endif
 
-PREF_JS_EXPORTS	= $(srcdir)/init/all.js
-
 EXTRA_DSO_LDOPTS = \
 		$(LIBS_DIR) \
 		$(MOZ_COMPONENT_LIBS) \
@@ -82,9 +80,13 @@ EXTRA_DSO_LDOPTS = \
 include $(topsrcdir)/config/rules.mk
 
 GARBAGE		+= $(addprefix $(DIST)/bin/defaults/pref/, \
-			all.js mailnews.js editor.js \
+			mailnews.js editor.js \
 			aix.js beos.js unix.js winpref.js os2prefs.js openvms.js photon.js)
 
+GARBAGE		+= greprefs.js
+
+GREPREF_FILES = $(topsrcdir)/xpinstall/public/xpinstall.js $(topsrcdir)/netwerk/base/public/security-prefs.js $(srcdir)/init/all.js
+
 # Optimizer bug with GCC 3.2.2 on OS/2
 ifeq ($(OS_ARCH), OS2)
 nsPrefService.$(OBJ_SUFFIX): nsPrefService.cpp
@@ -92,3 +94,10 @@ nsPrefService.$(OBJ_SUFFIX): nsPrefService.cpp
 	@$(MAKE_DEPS_AUTO_CXX)
 	$(ELOG) $(CCC) $(OUTOPTION)$@ -c $(COMPILE_CXXFLAGS:-O2=-O1) $(_VPATH_SRCS)
 endif
+
+
+greprefs.js: $(GREPREF_FILES)
+	$(PYTHON) $(topsrcdir)/config/Preprocessor.py $(PREF_PPFLAGS) $(DEFINES) $(ACDEFINES) $(XULPPFLAGS) $^ > $@
+
+libs:: greprefs.js
+	$(INSTALL) $^ $(DIST)/bin/
diff --git a/modules/libpref/src/nsPrefService.cpp b/modules/libpref/src/nsPrefService.cpp
index 79791f39328a..eef72eea44f1 100644
--- a/modules/libpref/src/nsPrefService.cpp
+++ b/modules/libpref/src/nsPrefService.cpp
@@ -464,8 +464,8 @@ static nsresult openPrefFile(nsIFile* aFile)
   if (NS_FAILED(rv)) 
     return rv;        
 
-  PRInt64 fileSize;
-  rv = aFile->GetFileSize(&fileSize);
+  PRUint32 fileSize;
+  rv = inStr->Available(&fileSize);
   if (NS_FAILED(rv))
     return rv;
 
@@ -640,18 +640,19 @@ static nsresult pref_LoadPrefsInDirList(const char *listId)
 static nsresult pref_InitInitialObjects()
 {
   nsCOMPtr<nsIFile> aFile;
+  nsCOMPtr<nsIFile> greprefsFile;
   nsCOMPtr<nsIFile> defaultPrefDir;
   nsresult          rv;
 
   // first we parse the GRE default prefs. This also works if we're not using a GRE, 
 
-  rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(defaultPrefDir));
+  rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(greprefsFile));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = defaultPrefDir->AppendNative(NS_LITERAL_CSTRING("greprefs"));
+  rv = greprefsFile->AppendNative(NS_LITERAL_CSTRING("greprefs.js"));
   NS_ENSURE_SUCCESS(rv, rv);
 
-  rv = pref_LoadPrefsInDir(defaultPrefDir, nsnull, 0);
+  rv = openPrefFile(greprefsFile);
   if (NS_FAILED(rv)) {
     NS_WARNING("Error parsing GRE default preferences. Is this an old-style embedding app?");
   }
diff --git a/netwerk/base/public/Makefile.in b/netwerk/base/public/Makefile.in
index 61e88b8e49b0..2d6b8179c54d 100644
--- a/netwerk/base/public/Makefile.in
+++ b/netwerk/base/public/Makefile.in
@@ -146,8 +146,6 @@ EXPORTS		= \
 		nsASocketHandler.h \
 		$(NULL)
 
-PREF_JS_EXPORTS = $(srcdir)/security-prefs.js
-
 include $(topsrcdir)/config/rules.mk
 
 DEFINES += -DIMPL_NS_NET
diff --git a/xpinstall/public/Makefile.in b/xpinstall/public/Makefile.in
index dcc1763e7cd7..0642763ac5bf 100644
--- a/xpinstall/public/Makefile.in
+++ b/xpinstall/public/Makefile.in
@@ -62,6 +62,4 @@ EXPORTS		= \
 		nsSoftwareUpdateIIDs.h \
 		$(NULL)
 
-PREF_JS_EXPORTS	= $(srcdir)/xpinstall.js
-
 include $(topsrcdir)/config/rules.mk