diff --git a/Makefile b/Makefile
index c79c85126f0c..d5d0742efeb2 100644
--- a/Makefile
+++ b/Makefile
@@ -1118,7 +1118,7 @@ ifdef building_out_of_srctree
 	$(Q)if [ -f $(srctree)/.config -o \
 		 -d $(srctree)/include/config -o \
 		 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \
-		echo >&2 "  $(srctree) is not clean, please run 'make ARCH=$(ARCH) mrproper'"; \
+		echo >&2 "  $(srctree) is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
 		echo >&2 "  in the '$(srctree)' directory.";\
 		/bin/false; \
 	fi;