diff --git a/.travis.yml b/.travis.yml
index 0e01869c33465bdf9d7467311f523d38cf4dce3b..339f2fa6e0366b4f346f9b351abcf705f4e919c5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,6 +14,7 @@ before_script:
   - composer install
   - npm install -g eslint@"<5.0.0"
   - npm install -g jshint@"2.9.6"
+  - npm install
 
 cache:
   directories:
@@ -22,4 +23,4 @@ cache:
     - $HOME/.composer/cache/files
 
 script:
-  - vendor/bin/phing eslint jshint phpunitfast phpcs-console php-cs-fixer-dryrun
+  - vendor/bin/phing eslint jshint phpunitfast phpcs-console php-cs-fixer-dryrun checkLessToSass
diff --git a/build.xml b/build.xml
index 9c951f0b69d88580caaab40915ea2be69d3f9b9c..4eda8c40594aad4e6ef30dffa4152a47e33406ac 100644
--- a/build.xml
+++ b/build.xml
@@ -131,6 +131,12 @@
     <exec command="jshint --config=${srcdir}/tests/jshint.json --exclude=themes/*/js/vendor --reporter=checkstyle ${srcdir}/themes &gt; ${builddir}/reports/jshint-checkstyle.xml" />
   </target>
 
+  <!-- Run LessToSass, error if there are uncommitted changes (used by Travis) -->
+  <target name="checkLessToSass">
+    <exec command="grunt lessToSass" checkreturn="true" passthru="true" />
+    <exec command="git diff --exit-code *.scss" checkreturn="true" passthru="true" />
+  </target>
+
   <!-- PHP API Documentation -->
   <target name="phpdoc">
     <!-- GET phpDocumentor.phar -->