diff --git a/lib/converter/untested.js b/lib/converter/untested.js
index 64168e0..a494b96 100644
--- a/lib/converter/untested.js
+++ b/lib/converter/untested.js
@@ -146,8 +146,8 @@ const saveUntestedFileSource = async (entryFile, options) => {
 
 const getUntestedCoverageData = async (entryList, options, coverageType) => {
 
-    // save all empty coverage
-    const dataId = Util.uid();
+    // save all empty coverage, 20 - 5(empty)
+    const dataId = Util.uid(15, 'empty');
     const results = {
         id: dataId
     };
@@ -166,15 +166,14 @@ const getUntestedCoverageData = async (entryList, options, coverageType) => {
     for (const entry of entryList) {
 
         // for raw report: source file
+        // id, url, source, sourceMap
         await saveUntestedFileSource(entry, options);
 
-        const { type, url } = entry;
-
         if (coverageType === 'istanbul') {
 
             // ===============================================
             const item = {
-                path: fileURLToPath(url),
+                path: fileURLToPath(entry.url),
                 statementMap: {},
                 fnMap: {},
                 branchMap: {},
@@ -189,20 +188,7 @@ const getUntestedCoverageData = async (entryList, options, coverageType) => {
         } else {
 
             // ===============================================
-            if (type === 'js') {
-                // empty js
-                entry.functions = entry.functions || [{
-                    functionName: '',
-                    ranges: [{
-                        startOffset: 0,
-                        endOffset: entry.source.length,
-                        count: 0
-                    }]
-                }];
-            } else {
-                // empty css
-                entry.ranges = entry.ranges || [];
-            }
+            Util.setEmptyV8Coverage(entry);
 
             const item = {
                 ... entry
diff --git a/lib/utils/util.js b/lib/utils/util.js
index be40d5d..7fa96ff 100644
--- a/lib/utils/util.js
+++ b/lib/utils/util.js
@@ -272,6 +272,27 @@ const Util = {
         return handler;
     },
 
+    setEmptyV8Coverage: (entry) => {
+        if (entry.type === 'css') {
+            // empty css
+            if (!entry.ranges) {
+                entry.ranges = [];
+            }
+        } else {
+            // empty js
+            if (!entry.functions) {
+                entry.functions = [{
+                    functionName: '',
+                    ranges: [{
+                        startOffset: 0,
+                        endOffset: entry.source ? entry.source.length : 0,
+                        count: 0
+                    }]
+                }];
+            }
+        }
+    },
+
     saveSourceCacheFile: async (sourceData, options, fileCache) => {
         const { cacheName, cachePath } = Util.getCacheFileInfo('source', sourceData.id, options.cacheDir);
 
diff --git a/lib/v8/v8.js b/lib/v8/v8.js
index 5b2b843..672063a 100644
--- a/lib/v8/v8.js
+++ b/lib/v8/v8.js
@@ -109,11 +109,11 @@ const initV8ListAndSourcemap = async (mcr, v8list) => {
             distFile: entry.distFile
         };
 
-        // coverage
-        if (data.type === 'js') {
-            data.functions = entry.functions;
-        } else {
+        // coverage info
+        if (data.type === 'css') {
             data.ranges = entry.ranges;
+        } else {
+            data.functions = entry.functions;
         }
 
         // resolve source path
@@ -213,10 +213,10 @@ const mergeV8Coverage = async (dataList, sourceCache, options) => {
     for (const id of mergeIds) {
         const itemList = mergeMap[id];
         const item = itemMap[id];
-        if (item.type === 'js') {
-            item.functions = await mergeJsFunctions(itemList);
-        } else {
+        if (item.type === 'css') {
             item.ranges = await mergeCssRanges(itemList);
+        } else {
+            item.functions = await mergeJsFunctions(itemList);
         }
     }
 
@@ -236,16 +236,21 @@ const mergeV8Coverage = async (dataList, sourceCache, options) => {
     const mergedList = emptyList.concat(Object.values(itemMap));
 
     // try to load coverage and source by id
-    for (const item of mergedList) {
-        const { id } = item;
-        const json = sourceCache.get(id);
+    for (const entry of mergedList) {
+        const json = sourceCache.get(entry.id);
         if (json) {
-            item.source = json.source;
-            item.sourceMap = json.sourceMap;
+            entry.source = json.source;
+            entry.sourceMap = json.sourceMap;
         } else {
-            Util.logError(`Not found source data: ${Util.relativePath(item.sourcePath)}`);
-            item.source = '';
+            Util.logError(`Not found source data: ${Util.relativePath(entry.sourcePath)}`);
+            entry.source = '';
+        }
+
+        // add empty coverage after source init
+        if (entry.empty) {
+            Util.setEmptyV8Coverage(entry);
         }
+
     }
 
     return mergedList;
diff --git a/test/test-merge.js b/test/test-merge.js
index ed8f7ae..be111b3 100644
--- a/test/test-merge.js
+++ b/test/test-merge.js
@@ -24,8 +24,6 @@ const coverageOptions = {
     assetsPath: '../assets',
     // lcov: true,
 
-    // all: ['test/mock/src', 'test/mock/node/lib'],
-
     sourcePath: (filePath) => {
         const list = ['monocart-coverage-reports/', 'coverage-v8/'];
         for (const str of list) {