diff --git a/src/Region.cpp b/src/Region.cpp
index e13effb..42450f2 100644
--- a/src/Region.cpp
+++ b/src/Region.cpp
@@ -3,6 +3,7 @@
 #ifdef OPENCV
     #include <opencv2/core/core.hpp>
     #include <opencv2/highgui/highgui.hpp>
+    #include <opencv2/imgproc.hpp>
 #endif
 
 #include "Layer.h"