diff --git a/.travis.yml b/.travis.yml
index 54d592c9..61cacfb3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,7 +31,7 @@ addons:
 # The different configurations we want to test. You could also do things like
 # change flags or use --stack-yaml to point to a different file.
 env:
-- ARGS="--jobs 2 --resolver nightly-2018-12-21" CACHE_NAME=NIGHTLY_2018_12_21_CV_3_4_5
+- ARGS="--jobs 2 --resolver lts-13.25" CACHE_NAME=LTS_13_25_CV_4_1_0
 
 before_install:
 - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
diff --git a/stack.yaml b/stack.yaml
index 613161ba..33bbfccf 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -4,9 +4,12 @@ packages:
 - opencv-examples/
 - opencv-extra/
 - opencv-extra-examples/
-flags: {}
+flags:
+  opencv:
+    opencv4: true
+  opencv-extra:
+    opencv4: true
 allow-newer: true
-
 extra-lib-dirs:
 - /usr/local/lib
 
diff --git a/travis-build-opencv b/travis-build-opencv
index 74c5a77f..a958a9ca 100755
--- a/travis-build-opencv
+++ b/travis-build-opencv
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -eux -o pipefail
 
-OPENCV_VERSION=${OPENCV_VERSION:-3.4.5}
+OPENCV_VERSION=${OPENCV_VERSION:-4.1.0}
 
 GRAPHICAL=${GRAPHICAL:-OFF}