diff --git a/lib/webpack-manifest-plugin/hooks.js b/lib/webpack-manifest-plugin/hooks.js
index c1a32e63..817bedf1 100644
--- a/lib/webpack-manifest-plugin/hooks.js
+++ b/lib/webpack-manifest-plugin/hooks.js
@@ -119,14 +119,16 @@ const normalModuleLoaderHook = ({ moduleAssets, assetTypeModuleAssets }, loaderC
   // the "emitFile" callback is never called on asset modules
   // so, we create a different map that can be used later in the "emit" hook
   if (['asset', 'asset/inline', 'asset/resource', 'asset/source'].includes(module.type)) {
-      Object.assign(assetTypeModuleAssets, {
       // This takes the userRequest (which is an absolute path) and turns it into
       // a relative path to the root context. This is done so that the string
       // will match asset.info.sourceFilename in the emit hook.
-      [relative(loaderContext.rootContext, module.userRequest)]: basename(
-        module.userRequest
-      )
-    });
+      let sourceFilename = relative(loaderContext.rootContext, module.userRequest);
+      // at this point, Windows paths use \ in their paths
+      // but in the emit hook, asset.info.sourceFilename fill have UNIX slashes
+      sourceFilename = sourceFilename.replace(/\\/g, '/');
+      Object.assign(assetTypeModuleAssets, {
+        [sourceFilename]: basename(module.userRequest),
+      });
   }
 
   // eslint-disable-next-line no-param-reassign