diff --git a/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp b/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
index 8b744c74f..c0adeb957 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmosManager.hpp
@@ -11,7 +11,7 @@
 namespace Slic3r {
 
 namespace UndoRedo {
-class Snapshot;
+struct Snapshot;
 }
 
 namespace GUI {