diff --git a/experimental_autoconf_flatpak.patch b/experimental_autoconf_flatpak.patch
new file mode 100644
index 0000000..44d943a
--- /dev/null
+++ b/experimental_autoconf_flatpak.patch
@@ -0,0 +1,23 @@
+diff --git a/extensions/pref/autoconfig/src/nsReadConfig.cpp b/extensions/pref/autoconfig/src/nsReadConfig.cpp
+index 06f54dd0ab77..54f08ac90104 100644
+--- a/extensions/pref/autoconfig/src/nsReadConfig.cpp
++++ b/extensions/pref/autoconfig/src/nsReadConfig.cpp
+@@ -247,16 +247,8 @@ nsresult nsReadConfig::openAndEvaluateJSFile(const char* aFileName,
+   nsCOMPtr<nsIInputStream> inStr;
+   if (isBinDir) {
+     nsCOMPtr<nsIFile> jsFile;
+-#if defined(MOZ_WIDGET_GTK)
+-    if (!mozilla::widget::IsRunningUnderFlatpakOrSnap()) {
+-#endif  // defined(MOZ_WIDGET_GTK)
+-      rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(jsFile));
+-#if defined(MOZ_WIDGET_GTK)
+-    } else {
+-      rv = NS_GetSpecialDirectory(NS_OS_SYSTEM_CONFIG_DIR,
+-                                  getter_AddRefs(jsFile));
+-    }
+-#endif  // defined(MOZ_WIDGET_GTK)
++    rv = NS_GetSpecialDirectory(NS_GRE_DIR, getter_AddRefs(jsFile));
++
+     if (NS_FAILED(rv)) return rv;
+ 
+     rv = jsFile->AppendNative(nsDependentCString(aFileName));
diff --git a/scripts/3_Configure_Source_Code.sh b/scripts/3_Configure_Source_Code.sh
index 16a14f2..c0bfdc6 100755
--- a/scripts/3_Configure_Source_Code.sh
+++ b/scripts/3_Configure_Source_Code.sh
@@ -174,6 +174,9 @@ patch -Np1 -i "${_PATCHES_DIR}/urlbarprovider-interventions.patch"
 # allow SearchEngines option in non-ESR builds
 patch -Np1 -i "${_PATCHES_DIR}/sed-patches/allow-searchengines-non-esr.patch"
 
+# experimental: allow enabling JPEG XL in non-nightly browser
+patch -Np1 -i "${CI_PROJECT_DIR}/experimental_autoconf_flatpak.patch"
+
 # remove search extensions (experimental)
 # patch -Np1 -i "${_PATCHES_DIR}/search-config.patch"
 cp "${_SOURCE_REPO_DIR}/assets/search-config.json" services/settings/dumps/main/search-config.json