diff --git a/mozilla/xpcom/build/Makefile.in b/mozilla/xpcom/build/Makefile.in
index 30bcb9efd3e..eaf56ec5543 100644
--- a/mozilla/xpcom/build/Makefile.in
+++ b/mozilla/xpcom/build/Makefile.in
@@ -99,11 +99,6 @@ ifneq (,$(filter mac cocoa,$(MOZ_WIDGET_TOOLKIT)))
 EXTRA_DSO_LDOPTS += $(DEPTH)/dist/lib/libmacmorefiles_s.a
 endif
 
-# Turn off grep filter for .def files
-ifeq ($(MOZ_WIDGET_TOOLKIT),os2)
-XPCOM_SWITCH	= 1
-endif
-
 # Force use of PIC
 FORCE_USE_PIC	= 1