diff --git a/Common.mk b/Common.mk
index fd775e77..c069ada4 100644
--- a/Common.mk
+++ b/Common.mk
@@ -46,20 +46,18 @@ $(call arduino_output,$(call ardmk_include) Configuration:)
 #
 # Detect OS
 
+GREP_CMD = grep
 ifeq ($(OS),Windows_NT)
     CURRENT_OS = WINDOWS
-    GREP_CMD = grep
 else
     UNAME_S := $(shell uname -s)
     ifeq ($(UNAME_S),Linux)
         CURRENT_OS = LINUX
-        GREP_CMD = grep
     endif
     ifeq ($(UNAME_S),Darwin)
         CURRENT_OS = MAC
         ifeq (, $(shell which gggrep))
             $(info Using macOS BSD grep, please install GNU grep to avoid warnings)
-            GREP_CMD = grep
         else
             GREP_CMD = ggrep
         endif