1 files changed, 1 insertions, 1 deletions
diff --git a/Sam.mk b/Sam.mk
index 7f3cd2b..f11554f 100644
--- a/Sam.mk
+++ b/Sam.mk
@@ -404,7 +404,7 @@ CFLAGS_STD += -std=gnu11
 CPPFLAGS += -DMD -D$(USB_TYPE) '-DUSB_PRODUCT=$(USB_PRODUCT)' '-DUSB_MANUFACTURER=$(USB_MANUFACTURER)'
 
 # Get extra define flags from boards.txt
-EXFLAGS := $(shell echo $(call PARSE_BOARD,$(BOARD_TAG),build.extra_flags) | grep -oE '(-D)\w+')
+EXFLAGS := $(shell echo $(call PARSE_BOARD,$(BOARD_TAG),build.extra_flags) | $(GREP) -oE '(-D)\w+')
 
 # Strip only defines from extra flags as boards file appends user {build.usb}
 CPPFLAGS += $(EXFLAGS)