diff --git a/stdlib/src/jet/Function0.java b/stdlib/src/jet/Function0.java
index 1e007ea1140..798339bfd53 100644
--- a/stdlib/src/jet/Function0.java
+++ b/stdlib/src/jet/Function0.java
@@ -19,6 +19,7 @@
  */
 package jet;
 
+/** A function with no arguments */
 public abstract class Function0<R> extends DefaultJetObject {
     public abstract R invoke();