diff --git a/environment.mk b/environment.mk
index a9ad5d3..8f89587 100644
--- a/environment.mk
+++ b/environment.mk
@@ -38,7 +38,7 @@ export SHELL
 
 # User-defined configuration file
 SITE_ENV ?= content/site-env
-SITE_ENV ::= $(strip ${site_env})
+SITE_ENV ::= $(strip ${SITE_ENV})
 
 ifeq ($(strip $(shell [ -r ${SITE_ENV} ] && echo ${SITE_ENV})),)
   $(info Generate a site configuration file first via `make configure`)