diff --git a/usr/bin/sandbox-app-launcher b/usr/bin/sandbox-app-launcher
index 5d4d96a..005822c 100755
--- a/usr/bin/sandbox-app-launcher
+++ b/usr/bin/sandbox-app-launcher
@@ -157,7 +157,16 @@ setup() {
 
   cat >> "${wrapper_script}" << 'EOF'
 #!/bin/bash
+EOF
+
+  ## Debugging.
+  if [ -o xtrace ]; then
+  cat >> "${wrapper_script}" << 'EOF'
+set -x
+EOF
+  fi
 
+  cat >> "${wrapper_script}" << 'EOF'
 xsession_d_file_list_executable=(
   "/etc/X11/Xsession.d/20torbrowser"
   "/etc/X11/Xsession.d/20uwt"