diff --git a/simgear/scene/viewer/ClusteredShading.cxx b/simgear/scene/viewer/ClusteredShading.cxx
index 97a72e79..9b112201 100644
--- a/simgear/scene/viewer/ClusteredShading.cxx
+++ b/simgear/scene/viewer/ClusteredShading.cxx
@@ -17,6 +17,7 @@
 #include "ClusteredShading.hxx"
 
 #include <thread>
+#include <algorithm>
 
 #include <osg/RenderInfo>
 #include <osg/Texture2D>