diff --git a/openbr/plugins/classification/dlib.cpp b/openbr/plugins/classification/dlib.cpp
index 0881429..905363d 100644
--- a/openbr/plugins/classification/dlib.cpp
+++ b/openbr/plugins/classification/dlib.cpp
@@ -1,5 +1,6 @@
 #include <opencv2/imgproc/imgproc.hpp>
 #include <dlib/image_processing/frontal_face_detector.h>
+#include <dlib/image_processing.h>
 #include <dlib/opencv.h>
 
 #include "openbr/plugins/openbr_internal.h"