diff --git a/build.sh b/build.sh
index b1ffd38..7194423 100755
--- a/build.sh
+++ b/build.sh
@@ -4,7 +4,7 @@ set -e
 set -x
 
 if [ -z "${RPI}" ] ; then
-  echo "${RPI} missing, exting"
+  echo "\$RPI missing, exting"
   exit 1
 fi