--- a/config/version.mk
+++ b/config/version.mk
@@ -41,17 +41,21 @@ INCLUDED_VERSION_MK=1
 # TODO:
 # PBI      : Private build info.  Not used currently.
 #            Guessing the best way would be to set an env var.
 # BINARY   : Binary name.  Not used currently.
 ifeq ($(MOZ_WIDGET_TOOLKIT),windows)
 ifndef RESFILE
 RCFILE=./module.rc
 RESFILE=./module.res
+ifdef MOZILLA_1_9_1_BRANCH
 _RC_STRING = -QUIET 1 -DEPTH $(MOZDEPTH) -TOPSRCDIR $(MOZILLA_SRCDIR) -BITS $(MOZ_BITS) -OBJDIR . -SRCDIR $(srcdir) -DISPNAME $(MOZ_APP_DISPLAYNAME) -APPVERSION $(MOZ_APP_VERSION)
+else
+_RC_STRING = -QUIET 1 -DEPTH $(MOZDEPTH) -TOPSRCDIR $(MOZILLA_SRCDIR) -OBJDIR . -SRCDIR $(srcdir) -DISPNAME $(MOZ_APP_DISPLAYNAME) -APPVERSION $(MOZ_APP_VERSION)
+endif
 ifneq ($(BUILD_OFFICIAL)_$(MOZILLA_OFFICIAL),_)
 _RC_STRING += -OFFICIAL 1
 endif
 ifdef MOZ_DEBUG
 _RC_STRING += -DEBUG 1
 endif
 ifdef MODULE
 _RC_STRING += -MODNAME $(MODULE)