diff --git a/build.bat b/build.bat
index 614280239..a091c1f1c 100755
--- a/build.bat
+++ b/build.bat
@@ -1,3 +1,4 @@
 @echo off
 REM convience bat file to build with
+if exist %JAVA_HOME%\lib\tools.jar set CLASSPATH=%CLASSPATH%;%JAVA_HOME%\lib\tools.jar
 java -classpath "%CLASSPATH%;lib\ant.jar" org.apache.tools.ant.Main %1 %2 %3 %4 %5