diff --git a/build.gradle.kts b/build.gradle.kts
index 8077a43..ba367c4 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -8,7 +8,7 @@ plugins {
 val serialization_version = "1.3.4"
 
 group = "net.sergeych"
-version = "0.0.6"
+version = "0.0.7"
 
 repositories {
     mavenCentral()
diff --git a/src/commonMain/kotlin/net.sergeych.bintools/DataSource.kt b/src/commonMain/kotlin/net.sergeych.bintools/DataSource.kt
index b97ed41..a12a409 100644
--- a/src/commonMain/kotlin/net.sergeych.bintools/DataSource.kt
+++ b/src/commonMain/kotlin/net.sergeych.bintools/DataSource.kt
@@ -16,6 +16,12 @@ interface DataSource {
 
     fun readByte(): Byte
 
+    /**
+     * true if there is no more data available and next read operation will surely
+     * throw EndOfData. Can return null if it is impossible to determine (for some
+     * async sources)
+     */
+    fun isEnd(): Boolean? = null
 
     fun readUByte() = readByte().toUByte()
 
@@ -50,6 +56,9 @@ fun ByteArray.toDataSource(): DataSource =
         var position = 0
             private set
 
+        @Suppress("RedundantNullableReturnType")
+        override fun isEnd(): Boolean? = position == size
+
         override fun readByte(): Byte =
             if (position < size) this@toDataSource[position++]
             else throw DataSource.EndOfData()
@@ -65,6 +74,9 @@ fun UByteArray.toDataSource(): DataSource =
         var position = 0
             private set
 
+        @Suppress("RedundantNullableReturnType")
+        override fun isEnd(): Boolean? = position == size
+
         override fun readByte(): Byte =
             if (position < size) this@toDataSource[position++].toByte()
             else throw DataSource.EndOfData()
diff --git a/src/commonMain/kotlin/net.sergeych.bipack/BipackDecoder.kt b/src/commonMain/kotlin/net.sergeych.bipack/BipackDecoder.kt
index f22a068..f63c24c 100644
--- a/src/commonMain/kotlin/net.sergeych.bipack/BipackDecoder.kt
+++ b/src/commonMain/kotlin/net.sergeych.bipack/BipackDecoder.kt
@@ -57,7 +57,8 @@ class BipackDecoder(
     override fun decodeEnum(enumDescriptor: SerialDescriptor): Int = input.readNumber<UInt>().toInt()
 
     override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
-        if (elementIndex >= elementsCount) return CompositeDecoder.DECODE_DONE
+        if (elementIndex >= elementsCount || input.isEnd() == true )
+            return CompositeDecoder.DECODE_DONE
         nextIsUnsigned = false
         for (a in descriptor.getElementAnnotations(elementIndex)) {
             when (a) {
diff --git a/src/commonMain/kotlin/net.sergeych.bipack/annotations.kt b/src/commonMain/kotlin/net.sergeych.bipack/annotations.kt
index 366e6f5..7be187c 100644
--- a/src/commonMain/kotlin/net.sergeych.bipack/annotations.kt
+++ b/src/commonMain/kotlin/net.sergeych.bipack/annotations.kt
@@ -4,9 +4,16 @@ import kotlinx.serialization.SerialInfo
 
 /**
  * If this annotation is presented in some @Serializable class definition, its instances
- * will be serialized with leading number of fields. This allows to extend class later
+ * will be serialized with the leading number of fields. This allows extending class later
  * providing new parameters __to the end of the class__ and _with default values__.
  *
+ * __IMPORTANT NOTE__. Since version 0.0.7 it's been also possible to use default values
+ * for non-serialized fields after the end-of-data. If the source reports it correctly, e.g.
+ * [net.sergeych.bintools.DataSource.isEnd] returns true, the unset fields are initialized
+ * with default value. This approach ___is not working when the loading instance is not the last
+ * in the deciding array!___, still it is useful to decode isolated objects. We recommend to
+ * use [Extendable] where needed and possible.
+ *
  * Whe deserializing such instances from previous version binaries, the new parameters
  * will get default values.
  *
diff --git a/src/commonTest/kotlin/bipack/BipackEncoderTest.kt b/src/commonTest/kotlin/bipack/BipackEncoderTest.kt
index 7cb24aa..01047e4 100644
--- a/src/commonTest/kotlin/bipack/BipackEncoderTest.kt
+++ b/src/commonTest/kotlin/bipack/BipackEncoderTest.kt
@@ -393,7 +393,16 @@ class BipackEncoderTest {
         assertEquals(xv, yv)
         println(xv)
         println(yv)
-
-
     }
+
+    @Test
+    fun testStrangeUnpack() {
+        @Serializable
+        data class SFoo(val code: Int,val s1: String?=null,val s2: String?=null)
+        val z = BipackEncoder.encode(117)
+        println(z.toDump())
+        val sf = BipackDecoder.decode<SFoo>(z)
+        println(sf)
+    }
+
 }
\ No newline at end of file