diff --git a/idea/src/org/jetbrains/kotlin/idea/roots/KotlinNonJvmSourceRootConverterProvider.kt b/idea/src/org/jetbrains/kotlin/idea/roots/KotlinNonJvmSourceRootConverterProvider.kt
index fcb28fb2989..29930314981 100644
--- a/idea/src/org/jetbrains/kotlin/idea/roots/KotlinNonJvmSourceRootConverterProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/roots/KotlinNonJvmSourceRootConverterProvider.kt
@@ -50,13 +50,11 @@ class KotlinNonJvmSourceRootConverterProvider : ConverterProvider("kotlin-non-jv
             JavaResourceRootType.TEST_RESOURCE
         )
 
-        private val TargetPlatform.stdlibDetector: ((Array<VirtualFile>) -> Boolean)?
-            get() = when (this) {
-                is JvmPlatform -> { roots -> JavaRuntimeDetectionUtil.getRuntimeJar(roots.toList()) != null }
-                is JsPlatform -> { roots -> JsLibraryStdDetectionUtil.getJsStdLibJar(roots.toList()) != null }
-                is CommonPlatform -> { roots -> getLibraryJar(roots, PathUtil.KOTLIN_STDLIB_COMMON_JAR_PATTERN) != null }
-                else -> null
-            }
+        private val PLATFORM_TO_STDLIB_DETECTORS: Map<TargetPlatform, (Array<VirtualFile>) -> Boolean> = mapOf(
+            JvmPlatform to { roots: Array<VirtualFile> -> JavaRuntimeDetectionUtil.getRuntimeJar(roots.toList()) != null },
+            JsPlatform to { roots: Array<VirtualFile> -> JsLibraryStdDetectionUtil.getJsStdLibJar(roots.toList()) != null },
+            CommonPlatform to { roots: Array<VirtualFile> -> getLibraryJar(roots, PathUtil.KOTLIN_STDLIB_COMMON_JAR_PATTERN) != null }
+        )
     }
 
     sealed class LibInfo {
@@ -88,14 +86,16 @@ class KotlinNonJvmSourceRootConverterProvider : ConverterProvider("kotlin-non-jv
         abstract val explicitKind: PersistentLibraryKind<*>?
         abstract fun getRoots(): Array<VirtualFile>
 
-        val platform by lazy {
-            val explicitKind = explicitKind
-            val kind = if (explicitKind is KotlinLibraryKind) explicitKind else detectLibraryKind(getRoots())
-            kind?.platform ?: JvmPlatform
-        }
+        val stdlibPlatform: TargetPlatform? by lazy {
+            val roots = getRoots()
+            for ((platform, detector) in PLATFORM_TO_STDLIB_DETECTORS) {
+                if (detector.invoke(roots)) {
+                    return@lazy platform
+                }
+            }
 
-        val isStdlib: Boolean
-            get() = platform.stdlibDetector?.invoke(getRoots()) ?: false
+            return@lazy null
+        }
     }
 
     class ConverterImpl(private val context: ConversionContext) : ProjectConverter() {
@@ -144,15 +144,12 @@ class KotlinNonJvmSourceRootConverterProvider : ConverterProvider("kotlin-non-jv
                         .asSequence()
                         .mapNotNull { createLibInfo(it, this) }
                         .forEach {
-                            when (val platform = it.platform) {
-                                is CommonPlatform -> {
-                                    if (!hasCommonStdlib && it.isStdlib) {
-                                        hasCommonStdlib = true
-                                    }
-                                }
-
-                                else -> {
-                                    if (it.isStdlib) return platform
+                            val stdlibPlatform = it.stdlibPlatform
+                            if (stdlibPlatform != null) {
+                                if (stdlibPlatform == CommonPlatform) {
+                                    hasCommonStdlib = true
+                                } else {
+                                    return stdlibPlatform
                                 }
                             }
                         }
@@ -173,6 +170,7 @@ class KotlinNonJvmSourceRootConverterProvider : ConverterProvider("kotlin-non-jv
                         .flatMap { it.getChildren(SourceFolderImpl.ELEMENT_NAME) }
                 }
 
+                @Suppress("UnstableApiUsage")
                 private fun ModuleSettings.isExternalModule(): Boolean {
                     return when {
                         rootElement.getAttributeValue(ExternalProjectSystemRegistry.EXTERNAL_SYSTEM_ID_KEY) != null -> true