diff --git a/kernel/Makefile b/kernel/Makefile
index 98e7b94f04..0cd1bdbc71 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -32,10 +32,10 @@ DEBUG?=
 
 ifeq ($(HASH),)
 HASH_COMMIT?=HEAD # Setting this is only really useful with the show-tag target
-HASH?=$(shell git ls-tree --full-tree $(HASH_COMMIT) -- $(CURDIR) | awk '{print $$3}')
+HASH:=$(shell git ls-tree --full-tree $(HASH_COMMIT) -- $(CURDIR) | awk '{print $$3}')
 
 ifneq ($(HASH_COMMIT),HEAD) # Others can't be dirty by definition
-DIRTY=$(shell  git update-index -q --refresh && git diff-index --quiet HEAD -- $(CURDIR) || echo "-dirty")
+DIRTY:=$(shell git update-index -q --refresh && git diff-index --quiet HEAD -- $(CURDIR) || echo "-dirty")
 endif
 endif