diff --git a/apps/web/src/components/settings/calendar-source-form.tsx b/apps/web/src/components/settings/calendar-source-form.tsx
index 234324c..378d92a 100644
--- a/apps/web/src/components/settings/calendar-source-form.tsx
+++ b/apps/web/src/components/settings/calendar-source-form.tsx
@@ -94,13 +94,14 @@ export function CalendarSourceForm({
     }
   }, [t]);
 
-  // Form is valid when name, type, and url are filled and url is https
+  // Form is valid when name, type, and url are filled and url passed validation.
+  // Do NOT call validateUrl here — it calls setUrlError which is a state update
+  // during render (React error #301). onChange/onBlur already set urlError.
   const isFormValid =
     name.trim() !== '' &&
     type !== '' &&
     url.trim() !== '' &&
-    !urlError &&
-    validateUrl(url);
+    !urlError;
 
   const handleSubmit = useCallback(
     async (e: React.FormEvent) => {