diff --git a/include/boost/math/ccmath/isinf.hpp b/include/boost/math/ccmath/isinf.hpp
index a07b42aabd..9df492a18a 100644
--- a/include/boost/math/ccmath/isinf.hpp
+++ b/include/boost/math/ccmath/isinf.hpp
@@ -18,7 +18,7 @@ constexpr bool isinf(T x) noexcept
 {
     if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
     {
-        if constexpr (std::is_signed_v<T>)
+        if constexpr (std::numeric_limits<T>::is_signed)
         {
             return x == std::numeric_limits<T>::infinity() || -x == std::numeric_limits<T>::infinity();
         }