diff --git a/README.md b/README.md
index 2d27f16..b3c258a 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,15 @@
 # High-Throughput Computing Notebooks
 
 This repository contains the source Dockerfiles for 
-CHTC's High-Throughput Computing Notebooks (HTC Notebook).
-Each notebook is based on one of the [Jupyter Docker Stacks](https://github.com/jupyter/docker-stacks),
+CHTC's High-Throughput Computing Notebooks (HTC Notebooks).
+Each notebook is based on one of the 
+[Jupyter Docker Stacks](https://github.com/jupyter/docker-stacks),
 as specified by their names.
 
-A HTC Notebook contains both a Jupyter Lab and a "personal" HTCondor that can run jobs locally.
-It can also be configured as (for example) part of a Jupyter Hub which connects users to a larger HTCondor pool.
+A HTC Notebook contains both a Jupyter Lab and a "personal" HTCondor that can 
+run jobs locally.
+It can also be configured as part of a Jupyter Hub which connects 
+users to a larger HTCondor pool.
 
 ## Quick Start
 
@@ -20,4 +23,4 @@ Replace `htc-scipy-notebook` with your preferred stack,
 and `latest` with your preferred tag.
 
 The `latest` tag will always point at the most recent version of that stack,
-but SHA-tagged previous version are available as well.
+but date-tagged previous version are available as well.
diff --git a/make.py b/make.py
index 2157005..ecdecc9 100644
--- a/make.py
+++ b/make.py
@@ -8,20 +8,33 @@
 NOTEBOOKS_DIR = ROOT / 'notebooks'
 TEMPLATE_DIR = ROOT / 'template'
 
-shutil.rmtree(NOTEBOOKS_DIR, ignore_errors = True)
-NOTEBOOKS_DIR.mkdir()
+# get the base Dockerfile text
+DF_TEMPLATE = (TEMPLATE_DIR / 'Dockerfile').read_text()
 
-(NOTEBOOKS_DIR / 'DO_NOT_MODIFY').write_text('DO NOT MODIFY ANYTHING IN THIS DIRECTORY\nIT IS GENERATED BY make.py\n')
 
-for base_image in (ROOT / 'BASE_IMAGES.txt').read_text().splitlines():
-    repo, image, tag = re.match(r'(.*)\/(.*):(.*)', base_image).groups()
+def main():
+    shutil.rmtree(NOTEBOOKS_DIR, ignore_errors = True)
+    NOTEBOOKS_DIR.mkdir()
 
-    our_image = 'htc-{}'.format(image)
+    (NOTEBOOKS_DIR / 'DO_NOT_MODIFY').write_text(
+        'DO NOT MODIFY ANYTHING IN THIS DIRECTORY\nIT IS GENERATED BY make.py\n'
+    )
 
-    image_dir = NOTEBOOKS_DIR / our_image
-    shutil.copytree(TEMPLATE_DIR, image_dir, ignore = lambda *_: ['Dockerfile'])
+    for base_image in (ROOT / 'BASE_IMAGES.txt').read_text().splitlines():
+        repo, image, tag = re.match(r'(.*)\/(.*):(.*)', base_image).groups()
 
-    df = image_dir / 'Dockerfile'
-    df_template = (TEMPLATE_DIR / 'Dockerfile').read_text()
-    df_text = df_template.replace('<BASE_IMAGE>', base_image)
-    df.write_text(df_text)
+        our_image = 'htc-{}'.format(image)
+
+        image_dir = NOTEBOOKS_DIR / our_image
+
+        # copy everything but the Dockerfile, which will be done in the next step
+        shutil.copytree(TEMPLATE_DIR, image_dir, ignore = lambda *_: ['Dockerfile'])
+
+        # write out the the modified Dockerfile for this image
+        df = image_dir / 'Dockerfile'
+        df_text = DF_TEMPLATE.replace('<BASE_IMAGE>', base_image)
+        df.write_text(df_text)
+
+
+if __name__ == '__main__':
+    main()