diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/karma/KotlinKarma.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/karma/KotlinKarma.kt
index 29a46c80263..145dad46a70 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/karma/KotlinKarma.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/karma/KotlinKarma.kt
@@ -202,6 +202,7 @@ class KotlinKarma(override val compilation: KotlinJsCompilation) :
         requiredDependencies.add(versions.webpack)
         requiredDependencies.add(versions.webpackCli)
         requiredDependencies.add(versions.kotlinSourceMapLoader)
+        requiredDependencies.add(versions.sourceMapLoader)
     }
 
     fun useCoverage(
diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpackConfig.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpackConfig.kt
index af12a088b28..4ee15bd449d 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpackConfig.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/KotlinWebpackConfig.kt
@@ -46,6 +46,7 @@ data class KotlinWebpackConfig(
 
             if (sourceMaps) {
                 it.add(versions.kotlinSourceMapLoader)
+                it.add(versions.sourceMapLoader)
             }
 
             if (devServer != null) {