diff --git a/README.md b/README.md
index 2b7e41e..b62dc0c 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ or
 ### Build tags
 
 * `cv2` - build with `OpenCV` 2.x ([go-opencv](https://github.com/lazywei/go-opencv))
-* `cv3` - build with `OpenCV` 3.x ([gocv](https://github.com/hybridgroup/gocv))
+* `cv4` - build with `OpenCV` 4.x ([gocv](https://github.com/hybridgroup/gocv))
 * `jpeg` - build with native Go `image/jpeg` instead of `libjpeg-turbo`
 
 ### Download
diff --git a/cam2ip_cv.go b/cam2ip_cv.go
index 1f73022..0a40ae6 100644
--- a/cam2ip_cv.go
+++ b/cam2ip_cv.go
@@ -1,4 +1,4 @@
-// +build cv2,cv3
+// +build cv2,cv4
 
 package main
 
diff --git a/camera/camera_const_cv.go b/camera/camera_const_cv.go
index d18c1bd..515a8e4 100644
--- a/camera/camera_const_cv.go
+++ b/camera/camera_const_cv.go
@@ -1,4 +1,4 @@
-// +build cv2 cv3
+// +build cv2 cv4
 
 package camera
 
diff --git a/camera/camera_const_linux.go b/camera/camera_const_linux.go
index 4e7fce8..82a249d 100644
--- a/camera/camera_const_linux.go
+++ b/camera/camera_const_linux.go
@@ -1,4 +1,4 @@
-// +build !cv2,!cv3
+// +build !cv2,!cv4
 
 package camera
 
diff --git a/camera/camera_cv2.go b/camera/camera_cv2.go
index af427ee..21ffe89 100644
--- a/camera/camera_cv2.go
+++ b/camera/camera_cv2.go
@@ -1,4 +1,4 @@
-// +build cv2,!cv3
+// +build cv2,!cv4
 
 // Package camera.
 package camera
diff --git a/camera/camera_cv3.go b/camera/camera_cv4.go
similarity index 99%
rename from camera/camera_cv3.go
rename to camera/camera_cv4.go
index 822c9f1..45576b1 100644
--- a/camera/camera_cv3.go
+++ b/camera/camera_cv4.go
@@ -1,4 +1,4 @@
-// +build cv3,!cv2
+// +build cv4,!cv2
 
 // Package camera.
 package camera
diff --git a/camera/camera_linux.go b/camera/camera_linux.go
index fde7e6e..9ff54c9 100644
--- a/camera/camera_linux.go
+++ b/camera/camera_linux.go
@@ -1,4 +1,4 @@
-// +build !cv2,!cv3
+// +build !cv2,!cv4
 
 // Package camera.
 package camera
diff --git a/camera/camera_windows.go b/camera/camera_windows.go
index ce813ba..82e97a9 100644
--- a/camera/camera_windows.go
+++ b/camera/camera_windows.go
@@ -1,4 +1,4 @@
-// +build !cv2,!cv3
+// +build !cv2,!cv4
 
 // Package camera.
 package camera
diff --git a/video/video_cv2.go b/video/video_cv2.go
index b1f4008..d9fbe91 100644
--- a/video/video_cv2.go
+++ b/video/video_cv2.go
@@ -1,4 +1,4 @@
-// +build cv2,!cv3
+// +build cv2,!cv4
 
 // Package video.
 package video
diff --git a/video/video_cv3.go b/video/video_cv4.go
similarity index 98%
rename from video/video_cv3.go
rename to video/video_cv4.go
index 2ba1254..33aaf60 100644
--- a/video/video_cv3.go
+++ b/video/video_cv4.go
@@ -1,4 +1,4 @@
-// +build cv3,!cv2
+// +build cv4,!cv2
 
 // Package video.
 package video