diff --git a/gradle/core/build.gradle b/gradle/core/build.gradle
index 829f987ec..a61894bbf 100644
--- a/gradle/core/build.gradle
+++ b/gradle/core/build.gradle
@@ -262,6 +262,9 @@ dependencies {
   // Dependencies needed for compiling stylesheets to javascript
   css 'com.google.closure-stylesheets:closure-stylesheets:1.5.0'
   css 'args4j:args4j:2.0.26'
+
+  // Tool dependencies.  used for doc generation.
+  compile files("${System.properties['java.home']}/../lib/tools.jar")
 }
 
 task jaxbToJava {