diff --git a/src/Math/MathTypeTraits.h b/src/Math/MathTypeTraits.h
index fb97bb8b6..efe47f3a6 100644
--- a/src/Math/MathTypeTraits.h
+++ b/src/Math/MathTypeTraits.h
@@ -19,6 +19,7 @@
  * @brief Class Magnum::Math::MathTypeTraits
  */
 
+#include <cstddef>
 #include <cmath>
 
 /** @brief Precision when testing floats for equality */