diff --git a/README.md b/README.md
index 3f3e4d5c..c44acbd2 100644
--- a/README.md
+++ b/README.md
@@ -72,6 +72,19 @@ GitHub Cards is available on jsdelivr now. Use widget hosted on jsdelivr:
 <script src="https://cdn.jsdelivr.net/gh/lepture/github-cards@latest/jsdelivr/widget.js"></script>
 ```
 
+## Building
+
+If you want to work on this project locally, you'll first need to clone it `git clone https://github.com/lepture/github-cards`
+
+Then you'll need to install a few build dependencies:
+
+* [python3](https://www.python.org/) (if not already installed, through your favorite package manager)
+* [npm](https://www.npmjs.com/) (through your favorite package manager, along with Node.js)
+* [uglifyjs](https://www.npmjs.com/package/uglify-js) through `sudo npm install -g uglify-js`
+* [cleancss](https://www.npmjs.com/package/clean-css-cli) through `sudo npm install -g clean-css-cli`
+
+Once all of this is installed, you should be all set to build the site ! Use `make build` to do so. You can then view the site by opening _\_site/index.html_ in your browser of choice, and start making changes (you'll need to rebuild the site every time you change the files in _src/_)
+
 ## Contribution
 
 This project is under the BSD License.
diff --git a/generate.py b/generate.py
index 018a28a4..28189e8f 100755
--- a/generate.py
+++ b/generate.py
@@ -47,15 +47,15 @@ def create_card(theme):
 
     css = shell(['cleancss', 'theme/%s.css' % theme])
 
-    with open('src/card.js', 'rb') as f:
+    with open('src/card.js', 'r') as f:
         content = f.read()
         content += GA % 'UA-21475122-2'
 
-    js = shell(['uglifyjs', '-m'], content)
+    js = shell(['uglifyjs', '-m'], content.encode())
 
-    out = html % (css, tinyhtml(template), js)
+    out = html % (css.decode(), tinyhtml(template), js.decode())
     with open('cards/%s.html' % theme, 'wb') as f:
-        f.write(out)
+        f.write(out.encode())
 
 
 def create_widget():
@@ -71,7 +71,7 @@ def create_widget():
             'var base = "%s";' % url
         )
 
-    js = shell(['uglifyjs', '-m'], content)
+    js = shell(['uglifyjs', '-m'], content.encode())
     with open('jsdelivr/widget.js', 'wb') as f:
         f.write(js)