diff --git a/.travis.yml b/.travis.yml
index 49b90ca..692c95c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,7 +16,7 @@ before_install:
   - ./travis-tool.sh bootstrap
 
 install:
-  - ./travis-tool.sh install_r testthat knitr
+  - ./travis-tool.sh install_r testthat knitr ggplot2
 
 script: 
   - ./travis-tool.sh run_tests