diff --git a/zundler/__main__.py b/zundler/__main__.py
index 0cb0615..8f370e6 100644
--- a/zundler/__main__.py
+++ b/zundler/__main__.py
@@ -6,6 +6,8 @@ def main():
     embed_assets(
         args.input_path,
         output_path=args.output_path,
+        append_pre=args.append_pre,
+        append_post=args.append_post,
     )
 
 
diff --git a/zundler/args.py b/zundler/args.py
index 7da2e55..874ea87 100644
--- a/zundler/args.py
+++ b/zundler/args.py
@@ -25,6 +25,20 @@ parser.add_argument(
     version=__version__,
 )
 
+parser.add_argument(
+    '-P', '--append-pre',
+    default="",
+    help='append JS code to inject_pre script (default: %(default)s)',
+)
+
+
+parser.add_argument(
+    '-p', '--append-post',
+    default="",
+    help='append JS code to inject_post script (default: %(default)s)',
+)
+
+
 parser.add_argument(
     'input_path',
     help='input path to the root HTML file',
diff --git a/zundler/embed.py b/zundler/embed.py
index c7e7b8c..625c41d 100644
--- a/zundler/embed.py
+++ b/zundler/embed.py
@@ -29,7 +29,7 @@ SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
 logger = logging.getLogger(__name__)
 
 
-def embed_assets(index_file, output_path=None):
+def embed_assets(index_file, output_path=None, append_pre="", append_post=""):
 
     init_files = {}
     for filename in [
@@ -55,10 +55,12 @@ def embed_assets(index_file, output_path=None):
     if not output_path:
         output_path = os.path.join(base_dir, new_base_name)
 
+    before = init_files['inject_pre.js'] + append_pre
+    after = init_files['inject_post.js'] + append_post
     file_tree = load_filetree(
         base_dir,
-        before=init_files['inject_pre.js'],
-        after=init_files['inject_post.js'],
+        before=before,
+        after=after,
         exclude_pattern=new_base_name,
     )
 
diff --git a/zundler/sphinxext/__init__.py b/zundler/sphinxext/__init__.py
index 175dc0a..5533575 100644
--- a/zundler/sphinxext/__init__.py
+++ b/zundler/sphinxext/__init__.py
@@ -50,6 +50,8 @@ class ZundlerBuilder(StandaloneHTMLBuilder):
             embed_assets(
                 input_path,
                 output_path=output_path,
+                append_pre=self.config.zundler_append_pre,
+                append_post=self.config.zundler_append_post,
             )
 
 
@@ -75,6 +77,18 @@ def setup(app):
         '',
     )
 
+    app.add_config_value(
+        'zundler_append_pre',
+        '',
+        '',
+    )
+
+    app.add_config_value(
+        'zundler_append_post',
+        '',
+        '',
+    )
+
     app.add_builder(ZundlerBuilder)
 
     return {