diff --git a/lib/utils.js b/lib/utils.js
index 5b782698e3..013d3ffe0a 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -576,25 +576,27 @@ exports.lookupFiles = function lookupFiles(filepath, extensions, recursive) {
   var stat;
 
   if (!fs.existsSync(filepath)) {
-    // Check all extensions, using first match found (if any)
-    if (
-      !extensions.some(function(ext) {
-        if (fs.existsSync(filepath + '.' + ext)) {
-          filepath += '.' + ext;
-          return true;
-        }
-      })
-    ) {
-      // Handle glob
-      files = glob.sync(filepath, {nodir: true});
-      if (!files.length) {
-        throw createNoFilesMatchPatternError(
-          'Cannot find any files matching pattern ' + exports.dQuote(filepath),
-          filepath
-        );
-      }
-      return files;
+    var pattern;
+    if (glob.hasMagic(filepath)) {
+      // Handle glob as is without extensions
+      pattern = filepath;
+    } else {
+      // glob pattern e.g. 'filepath+(.js|.ts)'
+      var strExtensions = extensions
+        .map(function(v) {
+          return '.' + v;
+        })
+        .join('|');
+      pattern = filepath + '+(' + strExtensions + ')';
+    }
+    files = glob.sync(pattern, {nodir: true});
+    if (!files.length) {
+      throw createNoFilesMatchPatternError(
+        'Cannot find any files matching pattern ' + exports.dQuote(filepath),
+        filepath
+      );
     }
+    return files;
   }
 
   // Handle file