diff --git a/source/recipes/devshell/env-var/main.adoc0 b/source/recipes/devshell/env-var/main.adoc0
index be66c5e..14b309d 100644
--- a/source/recipes/devshell/env-var/main.adoc0
+++ b/source/recipes/devshell/env-var/main.adoc0
@@ -21,9 +21,9 @@ $# cat flake.nix
 Here's a demonstration using the shell.
 
 ....
-$ echo "FOO=$FOO"
+$ echo "FOO=${FOO}"
 $# ../../../../../start-shell nix develop <<EOL
-$ echo "FOO=$FOO"
+$ echo "FOO=${FOO}"
 $# EOL
 ....