diff --git a/pkg/package.mk b/pkg/package.mk
index 96297159a..1e2971d5c 100644
--- a/pkg/package.mk
+++ b/pkg/package.mk
@@ -5,18 +5,8 @@ ORG?=linuxkit
 HASH?=$(shell git ls-tree HEAD -- ../$(notdir $(CURDIR)) | awk '{print $$3}')
 BASE_DEPS=Dockerfile Makefile
 
-# Add '-dirty' to hash if the repository is not clean. make does not
-# concatenate strings without spaces, so we use the documented trick
-# of replacing the space with nothing.
-DIRTY=$(shell git diff-index --quiet HEAD --; echo $$?)
-ifneq ($(DIRTY),0)
-HASH+=-dirty
-nullstring :=
-space := $(nullstring) $(nullstring)
-TAG=$(subst $(space),,$(HASH))
-else
-TAG=$(HASH)
-endif
+DIRTY=$(shell git diff-index --quiet HEAD -- ) || echo "-dirty")
+TAG=$(HASH)$(DIRTY)
 
 # Get a release tag, if present
 RELEASE=$(shell git tag -l --points-at HEAD)
@@ -35,7 +25,7 @@ tag: $(BASE_DEPS) $(DEPS)
 	docker build $(NET_OPT) -t $(ORG)/$(IMAGE):$(TAG) .
 
 push: tag
-ifneq ($(DIRTY),0)
+ifneq ($(DIRTY),)
 	$(error Your repository is not clean. Will not push package image.)
 endif
 	DOCKER_CONTENT_TRUST=1 docker pull $(ORG)/$(IMAGE):$(TAG) || \