diff --git a/format.h b/format.h
index 44fdde22..89c2ef70 100644
--- a/format.h
+++ b/format.h
@@ -774,7 +774,6 @@ class IsConvertibleToInt {
 
   static const T &get();
 
-  static yes &check(bool);
   static yes &check(char);
   static yes &check(signed char);
   static yes &check(unsigned char);