diff --git a/examples/build.xml b/examples/build.xml
index 61afd33d7e77bf5ea1ccdf52bc4fd9ee8d9b73d7..6109e1ae34b21d76e2b3b5782e2e816ba110113f 100644
--- a/examples/build.xml
+++ b/examples/build.xml
@@ -216,12 +216,12 @@ POSSIBILITY OF SUCH DAMAGE.
     </target>
 
     <target name="-post-jar" description="compiles all classes into a single utility jar for MV3500 course use of viskit">
-        <copy todir="${viskit.proj.lib.dir}">
+        <copy todir="${viskit.proj.lib.dir}" overwrite="true">
             <fileset dir="${dist.dir}">
                 <include name="${dist.name}.jar"/>
             </fileset>
         </copy>
-        <copy todir="${2024.cohort.assign.viskit.ex.proj.lib.dir}">
+        <copy todir="${2024.cohort.assign.viskit.ex.proj.lib.dir}" overwrite="true">
             <fileset dir="${dist.dir}">
                 <include name="${dist.name}.jar"/>
             </fileset>