diff --git a/routes/api.py b/routes/api.py
index 3c16d43..748b131 100644
--- a/routes/api.py
+++ b/routes/api.py
@@ -156,7 +156,11 @@ def vapid_public_key():
     
     # Join the split lines to remove all whitespace and newlines
     base64_key = "".join(match.group(1).split())
-    return jsonify({"public_key": base64_key})
+    
+    # Convert to URL-safe base64 for the PushManager API
+    url_safe_key = base64_key.replace('+', '-').replace('/', '_')
+    
+    return jsonify({"public_key": url_safe_key})
 
 
 @api_blueprint.route("/save-subscription", methods=["POST"])