diff --git a/src/libslic3r/Measure.hpp b/src/libslic3r/Measure.hpp
index b2e2008d15..9cc380dd2b 100644
--- a/src/libslic3r/Measure.hpp
+++ b/src/libslic3r/Measure.hpp
@@ -12,6 +12,11 @@ struct indexed_triangle_set;
 
 
 namespace Slic3r {
+
+#if ENABLE_GIZMO_MEASURE_WORLD_COORDINATES
+class TriangleMesh;
+#endif // ENABLE_GIZMO_MEASURE_WORLD_COORDINATES
+
 namespace Measure {