diff --git a/src/detail/challenge-encoder.hpp b/src/detail/challenge-encoder.hpp
index 9ef19a9..fb9d5d2 100644
--- a/src/detail/challenge-encoder.hpp
+++ b/src/detail/challenge-encoder.hpp
@@ -31,7 +31,7 @@
 {
 public:
   static Block
-  encodeDataContent(const CaState& request);
+  encodeDataContent(const ca::RequestState& request);
 
   static void
   decodeDataContent(const Block& data, RequesterState& state);