@@ -2,6 +2,9 @@

 # set the graph driver as the current graphdriver if not set

 DOCKER_GRAPHDRIVER := $(if $(DOCKER_GRAPHDRIVER),$(DOCKER_GRAPHDRIVER),$(shell docker info 2>&1 | grep "Storage Driver" | sed 's/.*: //'))

+export DOCKER_GRAPHDRIVER

+DOCKER_INCREMENTAL_BINARY := $(if $(DOCKER_INCREMENTAL_BINARY),$(DOCKER_INCREMENTAL_BINARY),1)

+export DOCKER_INCREMENTAL_BINARY

 # get OS/Arch of docker engine

 DOCKER_OSARCH := $(shell bash -c 'source hack/make/.detect-daemon-osarch && echo $${DOCKER_ENGINE_OSARCH:-$$DOCKER_CLIENT_OSARCH}')

@@ -20,7 +23,7 @@ DOCKER_ENVS := \

 	-e DOCKER_DEBUG \

 	-e DOCKER_EXPERIMENTAL \

 	-e DOCKER_GITCOMMIT \

-	-e DOCKER_GRAPHDRIVER=$(DOCKER_GRAPHDRIVER) \

+	-e DOCKER_GRAPHDRIVER \

 	-e DOCKER_INCREMENTAL_BINARY \

 	-e DOCKER_PORT \

 	-e DOCKER_REMAP_ROOT \

@@ -159,7 +159,7 @@ ORIG_BUILDFLAGS=( -tags "autogen netgo static_build sqlite_omit_load_extension $

 # When $DOCKER_INCREMENTAL_BINARY is set in the environment, enable incremental

 # builds by installing dependent packages to the GOPATH.

 REBUILD_FLAG="-a"

-if [ "$DOCKER_INCREMENTAL_BINARY" ]; then

+if [ "$DOCKER_INCREMENTAL_BINARY" == "1" ] || [ "$DOCKER_INCREMENTAL_BINARY" == "true" ]; then

 	REBUILD_FLAG="-i"

 fi

 ORIG_BUILDFLAGS+=( $REBUILD_FLAG )