diff --git a/aws-ssm-ec2-proxy-command.sh b/aws-ssm-ec2-proxy-command.sh
old mode 100644
new mode 100755
index 7ba74af..4ccefcb
--- a/aws-ssm-ec2-proxy-command.sh
+++ b/aws-ssm-ec2-proxy-command.sh
@@ -52,7 +52,7 @@ aws ssm send-command \
   --document-name 'AWS-RunShellScript' \
   --comment "Add an SSH public key to authorized_keys for ${ssh_public_key_timeout} seconds" \
   --parameters commands="\"
-    mkdir -p ~${ssh_user}/.ssh && cd $_ || exit 1
+    mkdir -p ~${ssh_user}/.ssh && cd \$_ || exit 1
     
     authorized_key='${ssh_public_key} ssm-session'
     echo \\\"\${authorized_key}\\\" >> authorized_keys