diff --git a/Makefile b/Makefile
index db79274c9a..31042b2e09 100644
--- a/Makefile
+++ b/Makefile
@@ -24,6 +24,8 @@ ifneq ($(OPENWRT_BUILD),1)
 
   override OPENWRT_BUILD=1
   export OPENWRT_BUILD
+  GREP_OPTIONS=
+  export GREP_OPTIONS
   include $(TOPDIR)/include/debug.mk
   include $(TOPDIR)/include/depends.mk
   include $(TOPDIR)/include/toplevel.mk
diff --git a/rules.mk b/rules.mk
index 0cb72ac6bc..2add087133 100644
--- a/rules.mk
+++ b/rules.mk
@@ -18,6 +18,9 @@ TMP_DIR:=$(TOPDIR)/tmp
 
 export SHELL=/usr/bin/env bash -c '. $(TOPDIR)/include/shell.sh; eval "$$2"' --
 
+GREP_OPTIONS=
+export GREP_OPTIONS
+
 qstrip=$(strip $(subst ",,$(1)))
 #"))