diff --git a/Gemfile.lock b/Gemfile.lock
index 4252446..11cd262 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -7,43 +7,49 @@ GEM
       thor (~> 0.19)
     colorator (1.1.0)
     concurrent-ruby (1.1.9)
-    em-websocket (0.5.2)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
-    ethon (0.14.0)
+      http_parser.rb (~> 0)
+    ethon (0.15.0)
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
-    faraday (1.5.1)
+    faraday (1.10.0)
       faraday-em_http (~> 1.0)
       faraday-em_synchrony (~> 1.0)
       faraday-excon (~> 1.1)
-      faraday-httpclient (~> 1.0.1)
+      faraday-httpclient (~> 1.0)
+      faraday-multipart (~> 1.0)
       faraday-net_http (~> 1.0)
-      faraday-net_http_persistent (~> 1.1)
+      faraday-net_http_persistent (~> 1.0)
       faraday-patron (~> 1.0)
-      multipart-post (>= 1.2, < 3)
+      faraday-rack (~> 1.0)
+      faraday-retry (~> 1.0)
       ruby2_keywords (>= 0.0.4)
     faraday-em_http (1.0.0)
     faraday-em_synchrony (1.0.0)
     faraday-excon (1.1.0)
     faraday-httpclient (1.0.1)
+    faraday-multipart (1.0.3)
+      multipart-post (>= 1.2, < 3)
     faraday-net_http (1.0.1)
     faraday-net_http_persistent (1.2.0)
     faraday-patron (1.0.0)
-    ffi (1.15.3)
+    faraday-rack (1.0.0)
+    faraday-retry (1.0.3)
+    ffi (1.15.5)
     forwardable-extended (2.6.0)
-    html-proofer (3.19.2)
+    html-proofer (3.19.3)
       addressable (~> 2.3)
       mercenary (~> 0.3)
-      nokogumbo (~> 2.0)
+      nokogiri (~> 1.12)
       parallel (~> 1.3)
       rainbow (~> 3.0)
       typhoeus (~> 1.3)
       yell (~> 2.0)
-    http_parser.rb (0.6.0)
-    i18n (1.8.10)
+    http_parser.rb (0.8.0)
+    i18n (1.10.0)
       concurrent-ruby (~> 1.0)
-    jekyll (4.2.0)
+    jekyll (4.2.2)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -62,7 +68,7 @@ GEM
       jekyll (>= 3.7, < 5.0)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-sass-converter (2.1.0)
+    jekyll-sass-converter (2.2.0)
       sassc (> 2.0.1, < 3.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
@@ -71,34 +77,32 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.5.1)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.4.0)
-    mini_portile2 (2.6.1)
+    mini_portile2 (2.8.0)
     multipart-post (2.1.1)
     neat (4.0.0)
       thor (~> 0.19)
-    nokogiri (1.12.5)
-      mini_portile2 (~> 2.6.1)
+    nokogiri (1.13.3)
+      mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    nokogumbo (2.0.5)
-      nokogiri (~> 1.8, >= 1.8.4)
-    octokit (4.21.0)
+    octokit (4.22.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
-    parallel (1.20.1)
+    parallel (1.21.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.6)
-    racc (1.5.2)
-    rainbow (3.0.0)
-    rb-fsevent (0.11.0)
+    racc (1.6.0)
+    rainbow (3.1.1)
+    rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)
-    rouge (3.26.0)
-    ruby2_keywords (0.0.4)
+    rouge (3.28.0)
+    ruby2_keywords (0.0.5)
     safe_yaml (1.0.5)
     sassc (2.4.0)
       ffi (~> 1.9)
@@ -110,7 +114,7 @@ GEM
     thor (0.20.3)
     typhoeus (1.4.0)
       ethon (>= 0.9.0)
-    unicode-display_width (1.7.0)
+    unicode-display_width (1.8.0)
     yell (2.2.2)
 
 PLATFORMS
diff --git a/nix/sources.json b/nix/sources.json
index 22d7dca..61e46ba 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -12,15 +12,15 @@
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "nixpkgs": {
-        "branch": "release-21.05",
+        "branch": "release-21.11",
         "description": "Nix Packages collection",
         "homepage": "",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "3c0f229486b1c51100a6f89d768273257817dbd1",
-        "sha256": "1vap2nccka44czvydah940xhlv9dldvcrpykxr5n9hv6h07yxkn8",
+        "rev": "2aca05b38a8e4f391fd07ea4fc69231a420a3873",
+        "sha256": "0jkblcr6hgzrk5y7mfr1nhw7jxln8izdxazidiakih2ps5pdyj0i",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/3c0f229486b1c51100a6f89d768273257817dbd1.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/2aca05b38a8e4f391fd07ea4fc69231a420a3873.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     }
 }