diff --git a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/DokkaPlugin.kt b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/DokkaPlugin.kt
index c30fc181936..313092dd7aa 100644
--- a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/DokkaPlugin.kt
+++ b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/DokkaPlugin.kt
@@ -8,6 +8,7 @@ import org.gradle.kotlin.dsl.register
 import org.gradle.kotlin.dsl.withType
 import org.gradle.util.GradleVersion
 import org.jetbrains.dokka.DokkaDefaults
+import java.util.Locale
 
 open class DokkaPlugin : Plugin<Project> {
     override fun apply(project: Project) {
@@ -106,7 +107,7 @@ open class DokkaPlugin : Plugin<Project> {
 
     private fun Project.configureEachAbstractDokkaTask() {
         tasks.withType<AbstractDokkaTask>().configureEach {
-            val formatClassifier = name.removePrefix("dokka").decapitalize()
+            val formatClassifier = name.removePrefix("dokka").replaceFirstChar { it.lowercase(Locale.getDefault()) }
             outputDirectory.convention(project.layout.buildDirectory.dir("dokka/$formatClassifier"))
             cacheRoot.set(DokkaDefaults.cacheRoot)
         }
diff --git a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/dokkaDefaultOutputDirectory.kt b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/dokkaDefaultOutputDirectory.kt
index 0a7ab5340c7..3e1f475d275 100644
--- a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/dokkaDefaultOutputDirectory.kt
+++ b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/dokkaDefaultOutputDirectory.kt
@@ -2,12 +2,13 @@ package org.jetbrains.dokka.gradle
 
 import org.gradle.api.Task
 import java.io.File
+import java.util.Locale
 
 internal fun Task.defaultDokkaOutputDirectory(): File {
     return defaultDokkaOutputDirectory(project.buildDir, name)
 }
 
 internal fun defaultDokkaOutputDirectory(buildDir: File, taskName: String): File {
-    val formatClassifier = taskName.removePrefix("dokka").decapitalize()
+    val formatClassifier = taskName.removePrefix("dokka").replaceFirstChar { it.lowercase(Locale.getDefault()) }
     return File(buildDir, "dokka${File.separator}$formatClassifier")
 }
diff --git a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/kotlin/isMainSourceSet.kt b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/kotlin/isMainSourceSet.kt
index 15989217b32..23d147eab21 100644
--- a/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/kotlin/isMainSourceSet.kt
+++ b/runners/gradle-plugin/src/main/kotlin/org/jetbrains/dokka/gradle/kotlin/isMainSourceSet.kt
@@ -5,6 +5,7 @@ import com.android.build.gradle.api.LibraryVariant
 import org.gradle.api.Project
 import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJvmAndroidCompilation
+import java.util.Locale
 
 internal fun Project.isMainSourceSet(sourceSet: KotlinSourceSet): Boolean {
     return isMainSourceSet(allCompilationsOf(sourceSet))
@@ -23,7 +24,7 @@ private fun isMainCompilation(compilation: KotlinCompilation): Boolean {
         }
     } catch (e: NoSuchMethodError) {
         // Kotlin Plugin version below 1.4
-        return !compilation.name.toLowerCase().endsWith("test")
+        return !compilation.name.lowercase(Locale.getDefault()).endsWith("test")
     }
     return compilation.name == "main"
 }
diff --git a/runners/gradle-plugin/src/test/kotlin/org/jetbrains/dokka/gradle/AndroidAutoConfigurationTest.kt b/runners/gradle-plugin/src/test/kotlin/org/jetbrains/dokka/gradle/AndroidAutoConfigurationTest.kt
index 116104e8283..af3d3c2bda7 100644
--- a/runners/gradle-plugin/src/test/kotlin/org/jetbrains/dokka/gradle/AndroidAutoConfigurationTest.kt
+++ b/runners/gradle-plugin/src/test/kotlin/org/jetbrains/dokka/gradle/AndroidAutoConfigurationTest.kt
@@ -6,6 +6,7 @@ import org.gradle.api.internal.project.ProjectInternal
 import org.gradle.kotlin.dsl.configure
 import org.gradle.kotlin.dsl.withType
 import org.gradle.testfixtures.ProjectBuilder
+import java.util.Locale
 import kotlin.test.*
 
 class AndroidAutoConfigurationTest {
@@ -47,7 +48,7 @@ class AndroidAutoConfigurationTest {
         project as ProjectInternal
         project.evaluate()
         dokkaTasks.flatMap { it.dokkaSourceSets }.forEach { sourceSet ->
-            if ("test" in sourceSet.name.toLowerCase()) {
+            if ("test" in sourceSet.name.lowercase(Locale.getDefault())) {
                 assertTrue(
                     sourceSet.suppress.get(),
                     "Expected source set `${sourceSet.name}` to be suppressed by default"