diff --git a/pom.xml b/pom.xml
index ecf798e..f2b38b0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -35,6 +35,7 @@
 
   <properties>
     <io7m.api.previousVersion>0.0.1-SNAPSHOT</io7m.api.previousVersion>
+    <io7m.java.targetJavaVersion>21</io7m.java.targetJavaVersion>
     <io7m.org.immutables.version>2.10.0</io7m.org.immutables.version>
   </properties>