diff --git a/include/boost/math/special_functions/expm1.hpp b/include/boost/math/special_functions/expm1.hpp
index f53e42ab2..fccf97bc3 100644
--- a/include/boost/math/special_functions/expm1.hpp
+++ b/include/boost/math/special_functions/expm1.hpp
@@ -20,6 +20,7 @@
 #include <boost/math/policies/error_handling.hpp>
 #include <boost/math/tools/rational.hpp>
 #include <boost/math/special_functions/math_fwd.hpp>
+#include <boost/math/special_functions/fpclassify.hpp>
 #include <boost/math/tools/assert.hpp>
 
 #if defined(__GNUC__) && defined(BOOST_MATH_USE_FLOAT128)