diff --git a/.travis.yml b/.travis.yml
index 14da7e966f2dc238069c94cfb02c568c1848d853..cdb5ec855f521b762f02d0a0a49f74db06c761b1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,7 +15,7 @@ matrix:
       php: 5.4
 before_install:
   - sudo apt-get update -qq
-  - sudo apt-get install -qq swig
+  - sudo apt-get install -qq swig php5-dev
 before_script:
   - phpenv config-add src/bindings/php/hammer.ini
 script: