diff --git a/portal/flatpak-portal.c b/portal/flatpak-portal.c
index c5eae51f5..03ba05aef 100644
--- a/portal/flatpak-portal.c
+++ b/portal/flatpak-portal.c
@@ -917,33 +917,37 @@ handle_spawn (PortalFlatpak         *object,
         }
     }
 
-    {
-      static const char * const mock_run_environ[] = { "FOO=bar", NULL };
+  /* Pass the calling instance's run-environ as the envp for spawning
+   * flatpak run, so it can make host-level decisions (DISPLAY, GL drivers,
+   * XDG_RUNTIME_DIR, etc.) based on the original environment. This must NOT
+   * go into --env-fd, because run-environ is host-like and --env-fd injects
+   * into the sandbox payload environment.
+   */
+  {
+    static const char * const mock_run_environ[] = { "FOO=bar", NULL };
 
-      if (testing)
-        env = g_strdupv ((GStrv) mock_run_environ);
-      else
-        env = flatpak_instance_get_run_environ (instance, &error);
+    if (testing)
+      env = g_strdupv ((GStrv) mock_run_environ);
+    else
+      env = flatpak_instance_get_run_environ (instance, &error);
 
-      if (env == NULL)
-        {
-          if (g_error_matches (error, G_FILE_ERROR, G_FILE_ERROR_NOENT))
-            {
-              g_warning ("Environment for \"flatpak run\" was not found, falling back to current environment");
-              env = g_strdupv (original_environ);
-            }
-          else
-            {
-              g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
-                                                     G_DBUS_ERROR_INVALID_ARGS,
-                                                     "Could not load environment for \"flatpak run\": %s",
-                                                     error->message);
-              return G_DBUS_METHOD_INVOCATION_HANDLED;
-            }
+    if (env == NULL)
+      {
+        if (!g_error_matches (error, G_FILE_ERROR, G_FILE_ERROR_NOENT))
+          {
+            g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                                   G_DBUS_ERROR_INVALID_ARGS,
+                                                   "Could not load environment for \"flatpak run\": %s",
+                                                   error->message);
+            return G_DBUS_METHOD_INVOCATION_HANDLED;
+          }
 
-          g_clear_error (&error);
-        }
-    }
+        g_clear_error (&error);
+        g_warning ("Environment for \"flatpak run\" was not found, "
+                   "falling back to current environment");
+        env = g_strdupv (original_environ);
+      }
+  }
 
   if ((flatpak = g_getenv ("FLATPAK_PORTAL_MOCK_FLATPAK")) != NULL)
     g_ptr_array_add (flatpak_argv, g_strdup (flatpak));