diff --git a/compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/AdditionalSourceProvider.kt b/compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/AdditionalSourceProvider.kt
index e7d747370f3..c6a400df83f 100644
--- a/compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/AdditionalSourceProvider.kt
+++ b/compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/AdditionalSourceProvider.kt
@@ -26,7 +26,7 @@ abstract class AdditionalSourceProvider(val testServices: TestServices) : Servic
     protected fun File.toTestFile(relativePath: String? = null): TestFile {
         return TestFile(
             relativePath?.let(Paths::get)?.resolve(name)?.toString() ?: name,
-            this.readText(),
+            this.useLines { it.joinToString("\n") },
             originalFile = this,
             startLineNumberInOriginalFile = 0,
             isAdditional = true,