diff --git a/.travis.yml b/.travis.yml
index de4569b..ba7956f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,6 +17,7 @@ before_cache:
 cache:
   ccache: true
   directories:
+    - $HOME/.cache/pip
     - $HOME/.gradle/caches/
     - $HOME/.gradle/wrapper/
     - $HOME/.android/build-cache
diff --git a/travis/install_extra_deps.sh b/travis/install_extra_deps.sh
index 987c2d0..1d7c544 100755
--- a/travis/install_extra_deps.sh
+++ b/travis/install_extra_deps.sh
@@ -6,8 +6,8 @@ orig_dir=$(pwd)
 
 sudo apt-get update -qq
 sudo apt-get install -qq python3-pip zlib1g-dev libjpeg-dev
-pip3 install --user meson==0.43.0
-pip3 install --user pillow
+pip3 install --user --upgrade pip wheel
+pip3 install --user pillow meson==0.43.0
 
 # ninja
 git clone git://github.com/ninja-build/ninja.git