diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/descriptors/ValueDescriptor.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/descriptors/ValueDescriptor.kt
index 38b509e7..e3acd07b 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/descriptors/ValueDescriptor.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/descriptors/ValueDescriptor.kt
@@ -75,7 +75,7 @@ class ValueDescriptor(override val config: Config) : Specific {
      *
      * @return
      */
-    var type: List<ValueType> by value().map {
+    var type: List<ValueType> by value {
         it?.list?.map { v -> ValueType.valueOf(v.string) } ?: emptyList()
     }
 
@@ -83,7 +83,7 @@ class ValueDescriptor(override val config: Config) : Specific {
         this.type = listOf(*t)
     }
 
-    var tags: List<String> by value().map { value ->
+    var tags: List<String> by value { value ->
         value?.list?.map { it.string } ?: emptyList()
     }
 
@@ -106,7 +106,7 @@ class ValueDescriptor(override val config: Config) : Specific {
      *
      * @return
      */
-    var allowedValues: List<Value> by value().map {
+    var allowedValues: List<Value> by value {
         it?.list ?: if (type.size == 1 && type[0] === ValueType.BOOLEAN) {
             listOf(True, False)
         } else {
diff --git a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/ConfigDelegates.kt b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/ConfigDelegates.kt
index 9baa802a..8b439a98 100644
--- a/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/ConfigDelegates.kt
+++ b/dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/ConfigDelegates.kt
@@ -1,5 +1,6 @@
 package hep.dataforge.meta
 
+import hep.dataforge.values.Null
 import hep.dataforge.values.Value
 import kotlin.jvm.JvmName
 
@@ -9,7 +10,7 @@ import kotlin.jvm.JvmName
 /**
  * A property delegate that uses custom key
  */
-fun <T> Configurable.value(default: T, key: String? = null) =
+fun Configurable.value(default: Any = Null, key: String? = null) =
     MutableValueDelegate(config, key, Value.of(default))
 
 fun <T> Configurable.value(default: T? = null, key: String? = null, transform: (Value?) -> T) =