diff --git a/pom.xml b/pom.xml
index 862907f..90ba716 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,6 +27,7 @@
   <properties>
     <com.io7m.xstructural.version>1.4.0</com.io7m.xstructural.version>
     <io7m.api.previousVersion>0.0.1-SNAPSHOT</io7m.api.previousVersion>
+    <io7m.java.targetJavaVersion>21</io7m.java.targetJavaVersion>
     <junit.version>5.8.2</junit.version>
     <logback.version>1.4.14</logback.version>
   </properties>