diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/KotlinRootNpmResolver.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/KotlinRootNpmResolver.kt
index 5c8c6557d4c..2dabc244c46 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/KotlinRootNpmResolver.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/KotlinRootNpmResolver.kt
@@ -185,10 +185,11 @@ internal class KotlinRootNpmResolver internal constructor(
 
     fun alreadyResolvedMessage(action: String) = "Cannot $action. NodeJS projects already resolved."
 
-    @Synchronized
     fun addProject(target: Project) {
-        check(state == State.CONFIGURING) { alreadyResolvedMessage("add new project: $target") }
-        projectResolvers[target.path] = KotlinProjectNpmResolver(target, this)
+        synchronized(projectResolvers) {
+            check(state == State.CONFIGURING) { alreadyResolvedMessage("add new project: $target") }
+            projectResolvers[target.path] = KotlinProjectNpmResolver(target, this)
+        }
     }
 
     operator fun get(projectPath: String) = projectResolvers[projectPath] ?: error("$projectPath is not configured for JS usage")
@@ -228,7 +229,7 @@ internal class KotlinRootNpmResolver internal constructor(
      * Don't use directly, use [KotlinNpmResolutionManager.installIfNeeded] instead.
      */
     internal fun prepareInstallation(logger: Logger): Installation {
-        synchronized(this@KotlinRootNpmResolver) {
+        synchronized(projectResolvers) {
             check(state == State.CONFIGURING) {
                 "Projects must be configuring"
             }
@@ -270,7 +271,7 @@ internal class KotlinRootNpmResolver internal constructor(
             services: ServiceRegistry,
             logger: Logger
         ): KotlinRootNpmResolution {
-            synchronized(this@KotlinRootNpmResolver) {
+            synchronized(projectResolvers) {
                 check(state == State.PROJECTS_CLOSED) {
                     "Projects must be closed"
                 }
diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/MayBeUpToDatePackageJsonTasksRegistry.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/MayBeUpToDatePackageJsonTasksRegistry.kt
index a91ab393e2f..b3b138dc313 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/MayBeUpToDatePackageJsonTasksRegistry.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/MayBeUpToDatePackageJsonTasksRegistry.kt
@@ -10,9 +10,10 @@ import org.gradle.api.provider.Provider
 import org.gradle.api.services.BuildService
 import org.gradle.api.services.BuildServiceParameters
 import org.jetbrains.kotlin.gradle.targets.js.npm.tasks.KotlinPackageJsonTask
+import java.util.concurrent.ConcurrentHashMap
 
 internal abstract class MayBeUpToDatePackageJsonTasksRegistry : BuildService<BuildServiceParameters.None> {
-    private val mayBeUpToDateTasks = mutableSetOf<String>()
+    private val mayBeUpToDateTasks = ConcurrentHashMap.newKeySet<String>()
 
     fun markForNpmDependenciesResolve(task: KotlinPackageJsonTask) {
         mayBeUpToDateTasks.add(task.path)