diff --git a/blog/builder.sh b/blog/builder.sh
index ed97ec5..37c7b79 100644
--- a/blog/builder.sh
+++ b/blog/builder.sh
@@ -1,3 +1,15 @@
 source $stdenv/setup
+
+# Install KaTeX for back-end rendering.
+HOME="." npm install katex
+
+# Build site with Hugo
 cp -r $src/* .
-hugo --baseUrl="https://danilafe.com" --destination=$out
+hugo --baseUrl="http://localhost:5000"
+
+# Render math in HTML and XML files.
+find public/ -regex "public/.*\.html" | xargs ruby $converter
+
+# Output result
+mkdir $out
+cp -r public/* $out/
diff --git a/blog/convert.rb b/blog/convert.rb
index cd6602e..86461ea 100644
--- a/blog/convert.rb
+++ b/blog/convert.rb
@@ -11,7 +11,7 @@ def perform_katex_sub(content)
     end
   end
   rendered = rendered.gsub /\$\$((?:[^\$]|$[^\$])*)\$\$/ do |match|
-    puts "  Rendering display #{$~[1][0..30].strip}"
+    puts "  Rendering display."
     Open3.popen3("$(npm bin)/katex -d") do |i, o, e, t|
       i.write $~[1]
       i.close
diff --git a/blog/default.nix b/blog/default.nix
index 4279979..10d9718 100644
--- a/blog/default.nix
+++ b/blog/default.nix
@@ -1,9 +1,9 @@
-{ stdenv, hugo, fetchgit }:
+{ stdenv, hugo, fetchgit, nodejs, ruby }:
 
 let
     url = "https://dev.danilafe.com/Web-Projects/blog-static.git";
-    rev = "b04d82f0b3d949c1d4cd64246cc9c9558241f9ed";
-    sha256 = "02w05ff3mb8x3x65822vzg8lil0q6w4rfkj098fa0lwv8wv6x4cy";
+    rev = "7f3883fb3994f8ae1a64446a88b729662c9244dc";
+    sha256 = "065by3rjg7a43dqdl5ib07c0xi86balb5x2l54jqnlh1hz00bd85";
 in
     stdenv.mkDerivation {
         name = "blog-static";
@@ -12,5 +12,6 @@ in
             inherit url rev sha256;
         };
         builder = ./builder.sh;
-        buildInputs = [ hugo ];
+        converter = ./convert.rb;
+        buildInputs = [ hugo nodejs (ruby.withPackages (ps: [ ps.nokogiri ])) ];
     }