diff --git a/attributes-kt/src/commonMain/kotlin/space/kscience/attributes/PolymorphicAttribute.kt b/attributes-kt/src/commonMain/kotlin/space/kscience/attributes/PolymorphicAttribute.kt
index b61d4c477..80767421a 100644
--- a/attributes-kt/src/commonMain/kotlin/space/kscience/attributes/PolymorphicAttribute.kt
+++ b/attributes-kt/src/commonMain/kotlin/space/kscience/attributes/PolymorphicAttribute.kt
@@ -21,11 +21,13 @@ public abstract class PolymorphicAttribute<T>(public val type: SafeType<T>) : At
 /**
  * Get a polymorphic attribute using attribute factory
  */
+@UnstableAttributesAPI
 public operator fun <T> Attributes.get(attributeKeyBuilder: () -> PolymorphicAttribute<T>): T? = get(attributeKeyBuilder())
 
 /**
  * Set a polymorphic attribute using its factory
  */
+@UnstableAttributesAPI
 public operator fun <O, T> AttributesBuilder<O>.set(attributeKeyBuilder: () -> PolymorphicAttribute<T>, value: T) {
     set(attributeKeyBuilder(), value)
 }
diff --git a/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationProblem.kt b/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationProblem.kt
index 18f552bda..b9530f83c 100644
--- a/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationProblem.kt
+++ b/kmath-optimization/src/commonMain/kotlin/space/kscience/kmath/optimization/OptimizationProblem.kt
@@ -24,7 +24,7 @@ public val <T> OptimizationProblem<T>.startPoint: Map<Symbol, T>
     get() = attributes[OptimizationStartPoint()] ?: error("Starting point not defined in $this")
 
 public fun <T> AttributesBuilder<OptimizationProblem<T>>.startAt(startingPoint: Map<Symbol, T>) {
-    set(::OptimizationStartPoint, startingPoint)
+    set(OptimizationStartPoint(), startingPoint)
 }