diff --git a/searx/static/themes/oscar/package.json b/searx/static/themes/oscar/package.json
index 008119e15..ea522b9d0 100644
--- a/searx/static/themes/oscar/package.json
+++ b/searx/static/themes/oscar/package.json
@@ -2,7 +2,7 @@
     "devDependencies": {
         "grunt": "~1.4.1",
         "grunt-cli": "^1.4.3",
-        "grunt-contrib-concat": "~1.0.1",
+        "grunt-contrib-concat": "~2.0.0",
         "grunt-contrib-copy": "^1.0.0",
         "grunt-contrib-jshint": "~3.1.1",
         "grunt-contrib-less": "~3.0.0",
diff --git a/searx/static/themes/simple/package.json b/searx/static/themes/simple/package.json
index b85d79076..4b0ffc4fd 100644
--- a/searx/static/themes/simple/package.json
+++ b/searx/static/themes/simple/package.json
@@ -3,7 +3,7 @@
     "grunt-cli": "^1.4.3",
     "grunt": "~1.4.1",
     "grunt-contrib-copy": "^1.0.0",
-    "grunt-contrib-concat": "~1.0.1",
+    "grunt-contrib-concat": "~2.0.0",
     "grunt-contrib-cssmin": "^4.0.0",
     "grunt-contrib-jshint": "~3.1.1",
     "grunt-contrib-less": "~3.0.0",