diff --git a/src/quartz_api/internal/service/uk_national/cache.py b/src/quartz_api/internal/service/uk_national/cache.py
index c3953d0..452c0f0 100644
--- a/src/quartz_api/internal/service/uk_national/cache.py
+++ b/src/quartz_api/internal/service/uk_national/cache.py
@@ -50,7 +50,7 @@ async def key_builder(
             repr(sorted(params)),
             repr(sorted(permissions)),
         ],
-    )
+    ).replace("False", "false").replace("True", "true")
 
     log.info(f"Cache key generated: {key}")