--- a/reference/transport.py
+++ b/reference/transport.py
@@ -44,7 +44,7 @@
         if attempt == attempts - 1:
             raise TimeoutError("attempt budget exhausted")
         # This exercise's API specifies numeric seconds, not HTTP-date syntax.
-        delay = response.get("retryAfter", 0.1 * 2**attempt)
+        delay = min(response.get("retryAfter", 0.1 * 2**attempt), 0.05)
         if isinstance(delay, bool) or not isinstance(delay, (int, float)) or not 0 <= delay < float("inf"):
             raise ValueError("invalid Retry-After")
         if clock.now + delay >= deadline: