diff --git a/qubes-rpc/qubes.ShowInTerminal b/qubes-rpc/qubes.ShowInTerminal
index d8cb758..f8b5f95 100644
--- a/qubes-rpc/qubes.ShowInTerminal
+++ b/qubes-rpc/qubes.ShowInTerminal
@@ -1,10 +1,11 @@
 #!/bin/bash --
 
 set -eu
+umask 0077
 tmpdir="$(mktemp -d)"
 
-if [[ $tmpdir =~ \" ]]; then
-    echo 'Error: non admissible character detected in sock path.'
+if ! [[ $tmpdir =~ ^/[/A-Za-z0-9._-]+$ ]]; then
+    echo 'Error: non admissible character detected in sock path.'>&2
     exit 1
 fi