diff --git a/frontend/src/components/settings/SettingInput.tsx b/frontend/src/components/settings/SettingInput.tsx
index b6df2348..62f336d7 100644
--- a/frontend/src/components/settings/SettingInput.tsx
+++ b/frontend/src/components/settings/SettingInput.tsx
@@ -121,7 +121,7 @@ const SettingInput: React.FC<RenderSettingInputProps> = ({
             label={t("label.fallback_block")}
             helperText={t("help.fallback_block")}
             multiple={false}
-            onChange={(_e, selected, ..._) => onChange(selected?.id || null)}
+            onChange={(_e, selected, ..._) => onChange(selected?.id || "")}
             {...rest}
           />
         );