diff --git a/build.gradle.kts b/build.gradle.kts
index 28bccc9b..734da38d 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -2,7 +2,7 @@ plugins {
     id("ru.mipt.npm.project")
 }
 
-val dataforgeVersion by extra("0.2.1-dev-2")
+val dataforgeVersion by extra("0.2.1-dev-3")
 
 val bintrayRepo by extra("dataforge")
 val githubProject by extra("dataforge-core")
diff --git a/dataforge-io/api/dataforge-io.api b/dataforge-io/api/dataforge-io.api
index 1b8f876b..417f531a 100644
--- a/dataforge-io/api/dataforge-io.api
+++ b/dataforge-io/api/dataforge-io.api
@@ -77,6 +77,10 @@ public final class hep/dataforge/io/EnvelopeBuilder : hep/dataforge/io/Envelope
 	public final fun setType (Ljava/lang/String;)V
 }
 
+public final class hep/dataforge/io/EnvelopeBuilderKt {
+	public static final fun Envelope (Lkotlin/jvm/functions/Function1;)Lhep/dataforge/io/Envelope;
+}
+
 public abstract interface class hep/dataforge/io/EnvelopeFormat : hep/dataforge/io/IOFormat {
 	public abstract fun getDefaultMetaFormat ()Lhep/dataforge/io/MetaFormatFactory;
 	public abstract fun readObject (Lkotlinx/io/Input;)Lhep/dataforge/io/Envelope;