diff --git a/ext/opencv/opencv.h b/ext/opencv/opencv.h
index 2f20551..97dc19f 100644
--- a/ext/opencv/opencv.h
+++ b/ext/opencv/opencv.h
@@ -78,7 +78,7 @@ extern "C" {
 #include "opencv2/ml/ml.hpp"
 #endif
 
-#ifdef HAVE_NONFREE_H
+#ifdef HAVE_OPENCV2_NONFREE_NONFREE_HPP
 #include "opencv2/nonfree/nonfree.hpp"
 #endif