diff --git a/.travis.yml b/.travis.yml
index 23f21afcba6da5d1c401dc5ddbb9f9127c3f3372..a433caa8f71d61ede076ca5061c184b4d09a2ca8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -28,6 +28,7 @@ before_install:
   - export PATH=${TRAVIS_BUILD_DIR}/buildroot/bin/:${PATH}
 
 install:
+  - pip install backports.functools_lru_cache
   - pip install -U platformio
 
 before_script: