diff --git a/Rendering/OSPRay/vtkOSPRayRendererNode.cxx b/Rendering/OSPRay/vtkOSPRayRendererNode.cxx
index be9e2360a01527bd94ace5f0443724975a69df02..53368767c5a1befa9fca2b9dab2142738a7f5919 100644
--- a/Rendering/OSPRay/vtkOSPRayRendererNode.cxx
+++ b/Rendering/OSPRay/vtkOSPRayRendererNode.cxx
@@ -36,6 +36,7 @@
 #include "ospray/ospray.h"
 #include "ospray/version.h"
 
+#include <algorithm>
 #include <cmath>
 
 namespace ospray {
diff --git a/Rendering/OSPRay/vtkOSPRayVolumeMapperNode.cxx b/Rendering/OSPRay/vtkOSPRayVolumeMapperNode.cxx
index c52cba6b8cc654c3fafd833b5e77794a85360411..78cbdad674264d32dd5875f031cbbf9950e334d7 100644
--- a/Rendering/OSPRay/vtkOSPRayVolumeMapperNode.cxx
+++ b/Rendering/OSPRay/vtkOSPRayVolumeMapperNode.cxx
@@ -27,6 +27,8 @@
 #include "vtkVolumeNode.h"
 #include "vtkVolumeProperty.h"
 
+#include <algorithm>
+
 #include "ospray/ospray.h"
 
 //============================================================================