diff --git a/benchmarks/build.gradle.kts b/benchmarks/build.gradle.kts
index 24471a9e4..020ef745f 100644
--- a/benchmarks/build.gradle.kts
+++ b/benchmarks/build.gradle.kts
@@ -1,6 +1,5 @@
 @file:Suppress("UNUSED_VARIABLE")
 
-import org.jetbrains.kotlin.gradle.tasks.KotlinJvmCompile
 import space.kscience.kmath.benchmarks.addBenchmarkProperties
 
 plugins {
@@ -81,7 +80,7 @@ benchmark {
     // Setup configurations
     targets {
         register("jvm")
-        register("js")
+//        register("js")
     }
 
     fun kotlinx.benchmark.gradle.BenchmarkConfiguration.commonConfiguration() {
@@ -152,18 +151,12 @@ benchmark {
     }
 }
 
-kotlin.sourceSets.all {
-    with(languageSettings) {
-        optIn("kotlin.contracts.ExperimentalContracts")
-        optIn("kotlin.ExperimentalUnsignedTypes")
-        optIn("space.kscience.kmath.UnstableKMathAPI")
-    }
-}
-
-tasks.withType<KotlinJvmCompile> {
-    kotlinOptions {
-        jvmTarget = "11"
-        freeCompilerArgs = freeCompilerArgs + "-Xjvm-default=all" + "-Xlambdas=indy"
+kotlin {
+    jvmToolchain(11)
+    compilerOptions {
+        optIn.addAll(
+            "space.kscience.kmath.UnstableKMathAPI"
+        )
     }
 }
 
diff --git a/build.gradle.kts b/build.gradle.kts
index d90529e08..57ff022f2 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -16,7 +16,7 @@ allprojects {
     }
 
     group = "space.kscience"
-    version = "0.4.0"
+    version = "0.4.1-dev"
 }
 
 subprojects {
diff --git a/buildSrc/build.gradle.kts b/buildSrc/build.gradle.kts
index ba4c391d8..beb2af7f6 100644
--- a/buildSrc/build.gradle.kts
+++ b/buildSrc/build.gradle.kts
@@ -1,4 +1,5 @@
 plugins {
+    kotlin("jvm") version "1.9.23"
     `kotlin-dsl`
     `version-catalog`
 }
@@ -25,10 +26,8 @@ dependencies {
 }
 
 kotlin {
-    jvmToolchain {
-        languageVersion.set(JavaLanguageVersion.of(11))
-    }
-    sourceSets.all {
-        languageSettings.optIn("kotlin.OptIn")
+    jvmToolchain(11)
+    compilerOptions {
+        optIn.add("kotlin.OptIn")
     }
 }
diff --git a/gradle.properties b/gradle.properties
index 319ce3df0..2b3b0c9ce 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,6 +9,7 @@ org.gradle.configureondemand=true
 org.gradle.jvmargs=-Xmx4096m
 org.gradle.parallel=true
 org.gradle.workers.max=4
-toolsVersion=0.15.2-kotlin-1.9.22
+
+toolsVersion=0.15.4-kotlin-2.0.0
 #kotlin.experimental.tryK2=true
 #kscience.wasm.disabled=true
\ No newline at end of file
diff --git a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/base64/base64.kt b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/base64/base64.kt
index cb4da44fe..bf0f9cd22 100644
--- a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/base64/base64.kt
+++ b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/base64/base64.kt
@@ -4,11 +4,6 @@
  */
 
 @file:Suppress(
-    "INTERFACE_WITH_SUPERCLASS",
-    "OVERRIDING_FINAL_MEMBER",
-    "RETURN_TYPE_MISMATCH_ON_OVERRIDE",
-    "CONFLICTING_OVERLOADS",
-    "NO_EXPLICIT_VISIBILITY_IN_API_MODE_WARNING",
     "ObjectPropertyName",
     "ClassName",
 )
diff --git a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/binaryen/index.binaryen.kt b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/binaryen/index.binaryen.kt
index 6380d9b6c..e673130c2 100644
--- a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/binaryen/index.binaryen.kt
+++ b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/binaryen/index.binaryen.kt
@@ -4,10 +4,6 @@
  */
 
 @file:Suppress(
-    "INTERFACE_WITH_SUPERCLASS",
-    "OVERRIDING_FINAL_MEMBER",
-    "RETURN_TYPE_MISMATCH_ON_OVERRIDE",
-    "CONFLICTING_OVERLOADS",
     "PropertyName",
     "ClassName", "ENUM_CLASS_IN_EXTERNAL_DECLARATION_WARNING",
 )
diff --git a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/lib.dom.WebAssembly.module_dukat.kt b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/lib.dom.WebAssembly.module_dukat.kt
index c3e79c864..2103fcdc9 100644
--- a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/lib.dom.WebAssembly.module_dukat.kt
+++ b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/lib.dom.WebAssembly.module_dukat.kt
@@ -6,10 +6,6 @@
 @file:JsQualifier("WebAssembly")
 
 @file:Suppress(
-    "INTERFACE_WITH_SUPERCLASS",
-    "OVERRIDING_FINAL_MEMBER",
-    "RETURN_TYPE_MISMATCH_ON_OVERRIDE",
-    "NO_EXPLICIT_VISIBILITY_IN_API_MODE_WARNING",
     "ClassName",
 )
 
@@ -22,78 +18,34 @@ import org.w3c.fetch.Response
 import space.kscience.kmath.internal.tsstdlib.PromiseLike
 import kotlin.js.Promise
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
-internal external interface CompileError {
-    companion object {
-        var prototype: CompileError
-    }
-}
+internal external interface CompileError 
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
 internal external interface Global {
     var value: Any
     fun valueOf(): Any
-
-    companion object {
-        var prototype: Global
-    }
 }
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
 @JsName("Instance")
 internal external interface Instance1 {
     var exports: Exports
-
-    companion object {
-        var prototype: Instance
-    }
 }
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
-internal external interface LinkError {
-    companion object {
-        var prototype: LinkError
-    }
-}
+internal external interface LinkError
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
 internal external interface Memory {
     var buffer: ArrayBuffer
     fun grow(delta: Number): Number
-
-    companion object {
-        var prototype: Memory
-    }
 }
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
-@JsName("Module")
-internal external interface Module1 {
-    companion object {
-        var prototype: Module
-        fun customSections(moduleObject: Module, sectionName: String): Array<ArrayBuffer>
-        fun exports(moduleObject: Module): Array<ModuleExportDescriptor>
-        fun imports(moduleObject: Module): Array<ModuleImportDescriptor>
-    }
-}
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
-internal external interface RuntimeError {
-    companion object {
-        var prototype: RuntimeError
-    }
-}
+internal external interface RuntimeError
+
 
-@Suppress("NESTED_CLASS_IN_EXTERNAL_INTERFACE")
 internal external interface Table {
     var length: Number
     fun get(index: Number): Function<*>?
     fun grow(delta: Number): Number
     fun set(index: Number, value: Function<*>?)
-
-    companion object {
-        var prototype: Table
-    }
 }
 
 internal external interface GlobalDescriptor {
diff --git a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/nonDeclarations.WebAssembly.kt b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/nonDeclarations.WebAssembly.kt
index ad97c259d..21e32aeab 100644
--- a/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/nonDeclarations.WebAssembly.kt
+++ b/kmath-ast/src/jsMain/kotlin/space/kscience/kmath/internal/webassembly/nonDeclarations.WebAssembly.kt
@@ -3,13 +3,6 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-@file:Suppress(
-    "INTERFACE_WITH_SUPERCLASS",
-    "OVERRIDING_FINAL_MEMBER",
-    "RETURN_TYPE_MISMATCH_ON_OVERRIDE",
-    "CONFLICTING_OVERLOADS",
-    "NO_EXPLICIT_VISIBILITY_IN_API_MODE_WARNING",
-)
 
 package space.kscience.kmath.internal.webassembly
 
diff --git a/kmath-ast/src/jvmTest/kotlin/space/kscience/kmath/ast/utils.kt b/kmath-ast/src/jvmTest/kotlin/space/kscience/kmath/ast/utils.kt
index f06137c4a..b48a8fdba 100644
--- a/kmath-ast/src/jvmTest/kotlin/space/kscience/kmath/ast/utils.kt
+++ b/kmath-ast/src/jvmTest/kotlin/space/kscience/kmath/ast/utils.kt
@@ -12,8 +12,6 @@ import space.kscience.kmath.expressions.Symbol
 import space.kscience.kmath.operations.Algebra
 import space.kscience.kmath.operations.Float64Field
 import space.kscience.kmath.operations.Int32Ring
-import kotlin.contracts.InvocationKind
-import kotlin.contracts.contract
 import space.kscience.kmath.asm.compile as asmCompile
 import space.kscience.kmath.asm.compileToExpression as asmCompileToExpression
 
@@ -43,7 +41,6 @@ private object PrimitiveAsmCompilerTestContext : CompilerTestContext {
 
 
 internal actual inline fun runCompilerTest(action: CompilerTestContext.() -> Unit) {
-    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
     action(GenericAsmCompilerTestContext)
     action(PrimitiveAsmCompilerTestContext)
 }
diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/ShapeND.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/ShapeND.kt
index 2b30d35e4..9a32d3a88 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/ShapeND.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/ShapeND.kt
@@ -6,7 +6,6 @@
 package space.kscience.kmath.nd
 
 import space.kscience.kmath.UnsafeKMathAPI
-import kotlin.jvm.JvmInline
 
 /**
  * A read-only ND shape
diff --git a/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/functions/testUtils/Rational.kt b/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/functions/testUtils/Rational.kt
index 0160b2c97..df7dfec79 100644
--- a/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/functions/testUtils/Rational.kt
+++ b/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/functions/testUtils/Rational.kt
@@ -159,7 +159,7 @@ class Rational {
     override fun equals(other: Any?): Boolean =
         when (other) {
             is Rational -> numerator == other.numerator && denominator == other.denominator
-            is Int -> numerator == other && denominator == 1L
+            is Int -> numerator == other.toLong() && denominator == 1L
             is Long -> numerator == other && denominator == 1L
             else -> false
         }
diff --git a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram.kt b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram.kt
index 7f6fb2d26..9ba20df1a 100644
--- a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram.kt
+++ b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram.kt
@@ -33,7 +33,7 @@ public interface Histogram<in T : Any, out V, out B : Bin<T, V>> {
     /**
      * Find existing bin, corresponding to given coordinates
      */
-    public operator fun get(point: Point<out T>): B?
+    public operator fun get(point: Point<T>): B?
 
     /**
      * Dimension of the histogram
@@ -57,7 +57,7 @@ public interface HistogramBuilder<in T, V> {
     /**
      * Increment appropriate bin with given value
      */
-    public fun putValue(point: Point<out T>, value: V = defaultValue)
+    public fun putValue(point: Point<T>, value: V = defaultValue)
 
 }
 
diff --git a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram1D.kt b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram1D.kt
index ef72f2630..75f18a5a4 100644
--- a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram1D.kt
+++ b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram1D.kt
@@ -42,7 +42,7 @@ public interface Histogram1DBuilder<in T : Any, V : Any> : HistogramBuilder<T, V
      */
     public fun putValue(at: T, value: V = defaultValue)
 
-    override fun putValue(point: Point<out T>, value: V) {
+    override fun putValue(point: Point<T>, value: V) {
         require(point.size == 1) { "Only points with single value could be used in Histogram1D" }
         putValue(point[0], value)
     }
diff --git a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/UniformHistogramGroupND.kt b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/UniformHistogramGroupND.kt
index 8a914530b..4a53ea1a0 100644
--- a/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/UniformHistogramGroupND.kt
+++ b/kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/UniformHistogramGroupND.kt
@@ -93,7 +93,7 @@ public class UniformHistogramGroupND<V : Any, A : Field<V>>(
         val hBuilder = object : HistogramBuilder<Double, V> {
             override val defaultValue: V get() = valueAlgebraND.elementAlgebra.one
 
-            override fun putValue(point: Point<out Double>, value: V) = with(valueAlgebraND.elementAlgebra) {
+            override fun putValue(point: Point<Double>, value: V) = with(valueAlgebraND.elementAlgebra) {
                 val index = getIndexOrNull(point)
                 ndCounter[index].add(value)
             }