diff --git a/onionshare_gui/tab/mode/receive_mode/__init__.py b/onionshare_gui/tab/mode/receive_mode/__init__.py
index ba1fc8c4..c35a492c 100644
--- a/onionshare_gui/tab/mode/receive_mode/__init__.py
+++ b/onionshare_gui/tab/mode/receive_mode/__init__.py
@@ -24,7 +24,7 @@ from onionshare.web import Web
 
 from ..history import History, ToggleHistory, ReceiveHistoryItem
 from .. import Mode
-from ....widgets import MinimumWidthWidget
+from ....widgets import MinimumWidthWidget, Alert
 
 
 class ReceiveMode(Mode):
@@ -135,6 +135,11 @@ class ReceiveMode(Mode):
         )
 
         if selected_dir:
+            # If we're running inside a flatpak package, the data dir must be inside ~/OnionShare
+            if self.common.gui.is_flatpak:
+                if not selected_dir.startswith(os.path.expanduser("~/OnionShare")):
+                    Alert(self.common, strings._("gui_receive_flatpak_data_dir"))
+
             self.common.log(
                 "ReceiveMode",
                 "data_dir_button_clicked",
diff --git a/share/locale/en.json b/share/locale/en.json
index 5e19c42d..87cfd60f 100644
--- a/share/locale/en.json
+++ b/share/locale/en.json
@@ -22,6 +22,7 @@
     "gui_receive_start_server": "Start Receive Mode",
     "gui_receive_stop_server": "Stop Receive Mode",
     "gui_receive_stop_server_autostop_timer": "Stop Receive Mode ({} remaining)",
+    "gui_receive_flatpak_data_dir": "Because you installed OnionShare using flatpak, you must save files to a folder in ~/OnionShare.",
     "gui_copy_url": "Copy Address",
     "gui_copy_hidservauth": "Copy HidServAuth",
     "gui_canceled": "Canceled",
@@ -209,4 +210,4 @@
     "mode_settings_receive_data_dir_label": "Save files to",
     "mode_settings_receive_data_dir_browse_button": "Browse",
     "mode_settings_website_disable_csp_checkbox": "Disable Content Security Policy header (allows your website to use third-party resources)"
-}
+}
\ No newline at end of file