diff --git a/Makefile b/Makefile
index b6c20fd..dcb2497 100644
--- a/Makefile
+++ b/Makefile
@@ -117,7 +117,7 @@
 	$(LESSC) --modify-var="basic=true" $(LESS_OPTS) $(CSS_MAIN) > $@
 
 $(NODE_MODULES_INSTALLED): package.json
-	npm install
+	NODE_ENV=development npm install
 	touch $(NODE_MODULES_INSTALLED)
 
 $(BUILD_DIR_EXISTS):