diff --git a/Makefile b/Makefile
index 42b571bfdb5c1a51478fa5c7e88ddc349477f1ca..f917cb336d20b723a349db52f9a24b14cc108289 100755
--- a/Makefile
+++ b/Makefile
@@ -215,9 +215,13 @@ checksum:
 
 .PHONY: clean
 clean:
-	rm -rf $(BUILD_DIR)
+	rm -rf $(BUILD_DIR)/*
 	rm -f pkg/minikube/assets/assets.go
 
+.PHONY: tmpfs-out
+tmpfs-out:
+	mount -t tmpfs -o size=10g tmpfs $(BUILD_DIR)/out
+
 .PHONY: gendocs
 gendocs: out/docs/minikube.md
 
diff --git a/pkg/minikube/constants/constants.go b/pkg/minikube/constants/constants.go
index 253773c6f1ffe5eb54fdce041e745fb017024923..86f69b415fdb0557c2cb684759628497e8058658 100644
--- a/pkg/minikube/constants/constants.go
+++ b/pkg/minikube/constants/constants.go
@@ -127,7 +127,7 @@ kubectl: {{.Kubeconfig}}`
 var DefaultIsoUrl = fmt.Sprintf("https://storage.googleapis.com/%s/minikube-%s.iso", minikubeVersion.GetIsoPath(), minikubeVersion.GetIsoVersion())
 var DefaultIsoShaUrl = DefaultIsoUrl + ShaSuffix
 
-var DefaultKubernetesVersion = "v1.12.4"
+var DefaultKubernetesVersion = "v1.13.2"
 
 var ConfigFilePath = MakeMiniPath("config")
 var ConfigFile = MakeMiniPath("config", "config.json")