diff --git a/Source/engine/surface.hpp b/Source/engine/surface.hpp
index 1ce6016d5..cdcd28bbb 100644
--- a/Source/engine/surface.hpp
+++ b/Source/engine/surface.hpp
@@ -169,7 +169,7 @@ public:
 	{
 	}
 
-	OwnedSurface(Size size)
+	explicit OwnedSurface(Size size)
 	    : OwnedSurface(size.width, size.height)
 	{
 	}