--- a/build/build.xml
+++ b/build/build.xml
@@ -290,6 +290,7 @@
         <delete dir="${build.classes}" quiet="true"/>
         <mkdir dir="${build.classes}"/>
         <javac encoding="iso-8859-1" debug="true" target="1.7"
+               source="1.7"
                srcdir="${src.dir}"
                sourcepath=""
                destdir="${build.classes}"
@@ -307,6 +308,7 @@
     <target name="compile.test.copyright.classes">
         <mkdir dir="${build.classes}"/>
         <javac encoding="iso-8859-1" debug="true" target="1.7"
+               source="1.7"
                srcdir="${test.dir}"
                destdir="${build.classes}"
                classpath="${jdk14.classpath}">
@@ -320,6 +322,7 @@
 
         <mkdir dir="${build.junit.classes}"/>
         <javac encoding="iso-8859-1" debug="true" target="1.7"
+               source="1.7"
                srcdir="${src.dir}"
                destdir="${build.junit.classes}"
                classpath="${jdk14.classpath}:${build.classes}:${bytecodelib}:${junitlib}">