diff --git a/mozilla/config/rules.mk b/mozilla/config/rules.mk
index 9a611a9c31d..18ddd813e1e 100644
--- a/mozilla/config/rules.mk
+++ b/mozilla/config/rules.mk
@@ -307,7 +307,7 @@ endif
 
 ALL_TRASH = \
 	$(GARBAGE) $(TARGETS) $(OBJS) $(PROGOBJS) LOGS TAGS a.out \
-	$(OBJS:.$(OBJ_SUFFIX)=.s) $(OBJS:.$(OBJ_SUFFIX)=.ii) \
+	$(filter-out $(ASFILES),$(OBJS:.$(OBJ_SUFFIX)=.s)) $(OBJS:.$(OBJ_SUFFIX)=.ii) \
 	$(OBJS:.$(OBJ_SUFFIX)=.i) \
 	$(HOST_PROGOBJS) $(HOST_OBJS) $(IMPORT_LIBRARY) $(DEF_FILE)\
 	$(EXE_DEF_FILE) so_locations _gen _stubs $(wildcard *.res) $(wildcard *.RES) \