diff --git a/Makefile b/Makefile
index ff1e3177d..a2715e4ef 100644
--- a/Makefile
+++ b/Makefile
@@ -13,9 +13,9 @@ LD_FLAGS := -X github.com/evcc-io/evcc/util.Version=$(VERSION) -X github.com/evc
 BUILD_ARGS := -trimpath -ldflags='$(LD_FLAGS)'
 
 # docker
-DOCKER_IMAGE := evcc/evcc
-DOCKER_TAG := testing
-PLATFORM := linux/amd64,linux/arm64,linux/arm/v6
+DOCKER_IMAGE ?= evcc/evcc
+DOCKER_TAG ?= testing
+PLATFORM ?= linux/amd64,linux/arm64,linux/arm/v6
 
 # gokrazy image
 GOK_DIR := packaging/gokrazy