diff --git a/src/bindings/cpp/hammer/hammer.hpp b/src/bindings/cpp/hammer/hammer.hpp
index f3939ab351865b3aa5a78540b3aa5450a20c5dee..c2fe11709e41718e568f1563b2331a812337ab85 100644
--- a/src/bindings/cpp/hammer/hammer.hpp
+++ b/src/bindings/cpp/hammer/hammer.hpp
@@ -93,7 +93,7 @@ namespace hammer {
   static inline Parser Token(const uint8_t *buf, size_t len) {
     return Parser(h_token(buf, len));
   }
-  static inline Parser Ch(char ch) {
+  static inline Parser Ch(uint8_t ch) {
     return Parser(h_ch(ch));
   }
   static inline Parser ChRange(uint8_t lower, uint8_t upper) {