--- build.xml
+++ build.xml
@@ -38,7 +38,7 @@
 
   <target name="compile" depends="prepare"
     description="Compiles the source code">
-    <javac srcdir="${src.dir}"
+    <javac source="1.6" target="1.6" srcdir="${src.dir}"
            destdir="${build.dir}"
            debug="${build.debug}">
       <classpath refid="project.classpath"/>
@@ -47,7 +47,7 @@
 
   <target name="compile-sample" depends="prepare"
     description="Compiles the sample code">
-    <javac srcdir="sample"
+    <javac source="1.6" target="1.6" srcdir="sample"
            destdir="${build.dir}"
            debug="${build.debug}">
       <classpath refid="project.classpath"/>
@@ -57,7 +57,7 @@
   <target name="compile-tests" depends="compile"
           if="junit.available"
     description="Compiles the test code">
-    <javac srcdir="${test.dir}"
+    <javac source="1.6" target="1.6" srcdir="${test.dir}"
            destdir="${build.dir}"
            debug="${build.debug}">
       <classpath refid="project.classpath"/>