diff --git a/utils/installer.sh b/utils/installer.sh
index 1717427..177042f 100755
--- a/utils/installer.sh
+++ b/utils/installer.sh
@@ -174,7 +174,8 @@ else
 fi
 
 ### Check emacs version
-if [ $(emacs --version 2>/dev/null | sed -n 's/.*[^0-9.]\([0-9]*\.[0-9.]*\).*/\1/p;q' | sed 's/\..*//g') -lt 24 ]
+emacs_version="$(emacs --version 2>/dev/null | sed -n 's/.*[^0-9.]\([0-9]*\.[0-9.]*\).*/\1/p;q' | sed 's/\..*//g')"
+if [ "${emacs_version:-0}" -lt 24 ]
 then
     printf "$YELLOW WARNING:$RESET Prelude depends on emacs $RED 24$RESET !\n"
 fi