diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index 454f9ce52..fc1af1a5d 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -338,7 +338,7 @@ struct atanh2_impl
   static inline Scalar run(const Scalar& x, const Scalar& r)
   {
     EIGEN_STATIC_ASSERT_NON_INTEGER(Scalar)
-    #if __cplusplus >= 201103L
+    #if (__cplusplus >= 201103L) && !defined(__CYGWIN__)
       using std::log1p;
       return log1p(2 * x / (r - x)) / 2;
     #else