diff --git a/common/src/main/java/net/neoforged/gradle/common/extensions/JavaVersionManager.java b/common/src/main/java/net/neoforged/gradle/common/extensions/JavaVersionManager.java
index 608d1057a..9621741ab 100644
--- a/common/src/main/java/net/neoforged/gradle/common/extensions/JavaVersionManager.java
+++ b/common/src/main/java/net/neoforged/gradle/common/extensions/JavaVersionManager.java
@@ -24,6 +24,6 @@ public void setJavaVersion(int javaVersion, String context) {
         }
 
         this.javaVersion = javaVersion;
-        project.getExtensions().getByType(JavaPluginExtension.class).getToolchain().getLanguageVersion().set(JavaLanguageVersion.of(javaVersion));
+        project.getExtensions().getByType(JavaPluginExtension.class).getToolchain().getLanguageVersion().convention(JavaLanguageVersion.of(javaVersion));
     }
 }