diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/sourceMap/SourceMap3Builder.java b/js/js.translator/src/org/jetbrains/kotlin/js/sourceMap/SourceMap3Builder.java
index 07b601bd6f8..af268fb3a85 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/sourceMap/SourceMap3Builder.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/sourceMap/SourceMap3Builder.java
@@ -127,6 +127,7 @@ public class SourceMap3Builder implements SourceMapBuilder {
 
     @Override
     public void addMapping(String source, int sourceLine, int sourceColumn) {
+        source = source.replace(File.separatorChar, '/');
         boolean newGroupStarted = previousGeneratedColumn == -1;
         if (newGroupStarted) {
             previousGeneratedColumn = 0;