diff --git a/mozilla/config/rules.mk b/mozilla/config/rules.mk
index 2e8f409546f..b8062a5bc0d 100644
--- a/mozilla/config/rules.mk
+++ b/mozilla/config/rules.mk
@@ -71,6 +71,10 @@ ifndef topsrcdir
 topsrcdir		= $(DEPTH)
 endif
 
+ifndef MOZILLA_DIR
+MOZILLA_DIR = $(DEPTH)
+endif
+
 ifndef INCLUDED_CONFIG_MK
 include $(topsrcdir)/config/config.mk
 endif
@@ -1131,11 +1135,11 @@ endif
 JAR_MANIFEST := jar.mn
 
 chrome::
-	@if test -f $(JAR_MANIFEST); then $(PERL) $(topsrcdir)/config/make-jars.pl -c -d $(DIST)/bin/chrome < $(JAR_MANIFEST); fi
+	@if test -f $(JAR_MANIFEST); then $(PERL) $(MOZILLA_DIR)/config/make-jars.pl -c -d $(DIST)/bin/chrome < $(JAR_MANIFEST); fi
 
 install:: chrome
 
-REGCHROME = $(PERL) $(DEPTH)/config/add-chrome.pl $(DIST)/bin/chrome/installed-chrome.txt
+REGCHROME = $(PERL) $(MOZILLA_DIR)/config/add-chrome.pl $(DIST)/bin/chrome/installed-chrome.txt
 
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