diff --git a/Makefile b/Makefile
index 3f2be1c..cf70e2f 100644
--- a/Makefile
+++ b/Makefile
@@ -52,7 +52,7 @@
 
 #############################################################################
 # Variables, functions, and helpers
-TMPDIR := $(shell mktemp -d "XXXXXX" --tmpdir=$(TMPDIR))
+TMPDIR := $(shell mktemp -d "$${TMPDIR:-/tmp}/XXXXXX")
 HEAD := $(shell git rev-parse HEAD)
 
 bundles := public/css public/js/bundle.js