diff --git a/ci-gui.py b/ci-gui.py
index dd08244..20f4526 100644
--- a/ci-gui.py
+++ b/ci-gui.py
@@ -642,7 +642,6 @@ class CustomInstallGUI(ttk.Frame):
         for path in self.readers.keys():
             self.update_status(path, InstallStatus.Waiting)
         self.disable_buttons()
-        self.log('Starting install...')
 
         if taskbar:
             taskbar.SetProgressState(self.hwnd, tbl.TBPF_NORMAL)
@@ -652,6 +651,16 @@ class CustomInstallGUI(ttk.Frame):
                                   skip_contents=self.skip_contents_var.get() == 1,
                                   overwrite_saves=self.overwrite_saves_var.get() == 1)
 
+        if not installer.check_for_id0():
+            self.show_error(f'id0 {installer.crypto.id0.hex()} was not found inside "Nintendo 3DS" on the SD card.\n'
+                            f'\n'
+                            f'Before using custom-install, you should use this SD card on the appropriate console.\n'
+                            f'\n'
+                            f'Otherwise, make sure the correct movable.sed is being used.')
+            return
+
+        self.log('Starting install...')
+
         # use the treeview which has been sorted alphabetically
         readers_final = []
         for k in self.treeview.get_children():
diff --git a/custominstall.py b/custominstall.py
index 06e938c..ae25f25 100644
--- a/custominstall.py
+++ b/custominstall.py
@@ -271,6 +271,10 @@ class CustomInstall:
         free_space = get_free_space(self.sd)
         return total_size, free_space
 
+    def check_for_id0(self):
+        sd_path = join(self.sd, 'Nintendo 3DS', self.crypto.id0.hex())
+        return isdir(sd_path)
+
     def start(self):
         if frozen:
             save3ds_fuse_path = join(script_dir, 'bin', 'save3ds_fuse')
@@ -723,6 +727,10 @@ if __name__ == "__main__":
     installer.event.update_percentage += percent_handle
     installer.event.on_error += error
 
+    if not installer.check_for_id0():
+        installer.event.on_error(f'Could not find id0 directory {installer.crypto.id0.hex()} '
+                                 f'inside Nintendo 3DS directory.')
+
     installer.prepare_titles(args.cia)
 
     if not args.skip_contents: