diff --git a/scripts/flatpak/run.sh b/scripts/flatpak/run.sh
index c0fc4667..e50adde1 100755
--- a/scripts/flatpak/run.sh
+++ b/scripts/flatpak/run.sh
@@ -1,21 +1,43 @@
-#!/bin/sh
+#!/bin/bash
 
 die()
 {
         echo "$@"
+
+	if command -v zenity > /dev/null; then
+		zenity --error --text="$*"
+	fi
+
         exit 1
 }
 
+if [[ -z "$FLATPAK_ID" ]]; then
+	die "This script is only for Flatpak."
+fi
+
+if [[ "$FLATPAK_ID" == *.Compat.i386 ]]; then
+	if [[ ! -e /lib/i386-linux-gnu/ld-linux.so.2 ]]; then
+		source /etc/os-release
+
+		die "Can't find 32-bit runtime extension. Try running 'flatpak install org.freedesktop.Platform.Compat.i386//$VERSION_ID'."
+	fi
+
+	if [[ ! -e /lib/i386-linux-gnu/libGL.so.1 ]]; then
+		die "Can't find 32-bit OpenGL runtime extension. Try running 'flatpak install org.freedesktop.Platform.GL32.default'"
+	fi
+fi
+
+
 echo "Xash3D FWGS installed as Flatpak."
 
 # https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
 # $XDG_DATA_HOME defines the base directory relative to which user-specific data files should be stored.
 # If $XDG_DATA_HOME is either not set or empty, a default equal to $HOME/.local/share should be used.
-if [ -z "$XDG_DATA_HOME" ]; then
+if [[ -z "$XDG_DATA_HOME" ]]; then
         export XDG_DATA_HOME="$HOME/.local/share"
 fi
 
-if [ -z "$XASH3D_BASEDIR" ]; then
+if [[ -z "$XASH3D_BASEDIR" ]]; then
         export XASH3D_BASEDIR="$XDG_DATA_HOME/xash3d-fwgs/"
 fi
 
@@ -23,22 +45,22 @@ mkdir -p "$XASH3D_BASEDIR"
 cd "$XASH3D_BASEDIR" || die "Can't cd into $XASH3D_BASEDIR"
 echo "XASH3D_BASEDIR is $XASH3D_BASEDIR"
 
-if [ -z "$XASH3D_RODIR" ]; then
+if [[ -z "$XASH3D_RODIR" ]]; then
         # TODO: detect by libraryfolders.vdf and installed apps
-        STEAMDIRS="\
-                $HOME/.local/share/Steam/steamapps/common \
+        STEAMDIRS=" \
+                $XDG_DATA_HOME/Steam/steamapps/common \
                 $HOME/.var/app/com.valvesoftware.Steam/.local/share/Steam/steamapps/common \
                 $HOME/.steam/steam/steamapps/common"
         HALFLIFEDIR="Half-Life"
 
         for i in $STEAMDIRS; do
-                if [ ! -d "$i" ]; then
+                if [[ ! -d "$i" ]]; then
                         continue
                 fi
 
                 echo "Detected Steam library in $i, probing Half-Life..."
 
-                if [ ! -d "$i/$HALFLIFEDIR" ]; then
+                if [[ ! -d "$i/$HALFLIFEDIR" ]]; then
                         continue
                 fi
 
@@ -50,7 +72,7 @@ if [ -z "$XASH3D_RODIR" ]; then
 fi
 echo "XASH3D_RODIR is $XASH3D_RODIR"
 
-if [ -z "$XASH3D_EXTRAS_PAK1" ]; then
+if [[ -z "$XASH3D_EXTRAS_PAK1" ]]; then
         export XASH3D_EXTRAS_PAK1=/app/share/xash3d/valve/extras.pk3
 fi
 echo "XASH3D_EXTRAS_PAK1 is $XASH3D_EXTRAS_PAK1"