diff --git a/Gemfile.lock b/Gemfile.lock
index 8b6363b..2936b2c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -16,8 +16,11 @@ GEM
       thread_safe (~> 0.1)
       tzinfo (~> 1.1)
     addressable (2.3.6)
-    bootstrap-sass (3.3.1.0)
-      sass (~> 3.2)
+    autoprefixer-rails (9.8.4)
+      execjs
+    bootstrap-sass (3.4.1)
+      autoprefixer-rails (>= 5.2.1)
+      sassc (>= 2.0.0)
     celluloid (0.16.0)
       timers (~> 4.0.0)
     chunky_png (1.3.8)
@@ -117,6 +120,8 @@ GEM
       ffi (>= 0.5.0, < 2)
     redcarpet (3.2.2)
     sass (3.4.25)
+    sassc (2.4.0)
+      ffi (~> 1.9)
     slim (3.0.0)
       temple (~> 0.7.3)
       tilt (>= 1.3.3, < 2.1)