diff --git a/include/boost/config/platform/cygwin.hpp b/include/boost/config/platform/cygwin.hpp
index 0fd2ebe2..41fcaa10 100644
--- a/include/boost/config/platform/cygwin.hpp
+++ b/include/boost/config/platform/cygwin.hpp
@@ -12,6 +12,8 @@
 #define BOOST_NO_CWCHAR
 #define BOOST_NO_SWPRINTF
 #define BOOST_HAS_DIRENT_H
+#define BOOST_HAS_LOG1P
+#define BOOST_HAS_EXPM1
 
 //
 // Threading API:
@@ -46,3 +48,4 @@
 
 
 
+