diff --git a/src/Magnum/Math/Math.h b/src/Magnum/Math/Math.h
index 3c17c6e71..6b432f932 100644
--- a/src/Magnum/Math/Math.h
+++ b/src/Magnum/Math/Math.h
@@ -39,6 +39,8 @@ namespace Magnum { namespace Math {
 /** @todo Denormals to zero */
 
 #ifndef DOXYGEN_GENERATING_OUTPUT
+template<std::size_t> class BoolVector;
+
 /* Class Constants used only statically */
 
 template<UnsignedInt, UnsignedInt, class> class Bezier;