diff --git a/Makefile b/Makefile
index 4d8f68b..a3996e4 100644
--- a/Makefile
+++ b/Makefile
@@ -1,16 +1,13 @@
 .PHONY: build clean schemas
 
-MAKEFILE_DIR := $(patsubst %/,%,$(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
-KUBE_VERSION := $(strip $(shell cat $(MAKEFILE_DIR)/ci/kube-version 2>/dev/null))
-ifeq ($(KUBE_VERSION),)
-$(error cannot read $(MAKEFILE_DIR)/ci/kube-version)
-endif
-
 # Build a kustomization path to manifests directory
 # Usage: make build clusters/au-syd1/bootstrap
 build:
-	@mkdir -p manifests/$(filter-out $@,$(MAKECMDGOALS))
-	@kustomize build --enable-helm --helm-kube-version $(KUBE_VERSION) $(filter-out $@,$(MAKECMDGOALS)) --output manifests/$(filter-out $@,$(MAKECMDGOALS))
+	@kube_version="$$(cat ci/kube-version)"; \
+	if [ -z "$$kube_version" ]; then echo "cannot read ci/kube-version" >&2; exit 1; fi; \
+	target="$(filter-out $@,$(MAKECMDGOALS))"; \
+	mkdir -p "manifests/$$target"; \
+	kustomize build --enable-helm --helm-kube-version "$$kube_version" "$$target" --output "manifests/$$target"
 
 # Generate JSON schemas from CRDs and Kubernetes swagger spec (run manually, results committed)
 schemas: