diff --git a/openflexure_microscope/common/flask_labthings/quick.py b/openflexure_microscope/common/flask_labthings/quick.py
index 97f919a8..2f9f5ed4 100644
--- a/openflexure_microscope/common/flask_labthings/quick.py
+++ b/openflexure_microscope/common/flask_labthings/quick.py
@@ -20,7 +20,7 @@ def create_app(
 
     # Handle CORS
     if handle_cors:
-        cors_handler = CORS(app, resources=r"{prefix}/*")
+        cors_handler = CORS(app, resources=f"{prefix}/*")
 
     # Handle errors
     if handle_errors: