diff --git a/src/Magnum/Math/Math.h b/src/Magnum/Math/Math.h
index d735a39b7..1a445d30c 100644
--- a/src/Magnum/Math/Math.h
+++ b/src/Magnum/Math/Math.h
@@ -41,7 +41,7 @@ namespace Magnum { namespace Math {
 #ifndef DOXYGEN_GENERATING_OUTPUT
 template<std::size_t> class BoolVector;
 
-template<class> class Constants;
+template<class> struct Constants;
 
 template<class> class Complex;
 template<class> class Dual;