diff --git a/zooms_generator.py b/zooms_generator.py
index f31ff3d..6d60ee7 100644
--- a/zooms_generator.py
+++ b/zooms_generator.py
@@ -3,10 +3,10 @@
 # CC-BY-NC-SA https://git.aribaud.net/caribaud/melpomene/
 
 import sys
-import re
-import xml.etree.ElementTree as ET
-import argparse
-
+from argparse import ArgumentParser
+from xml.etree import ElementTree
+from xml.etree.ElementTree import Element
+from typing import Any
 from pathlib import Path
 
 
@@ -14,13 +14,19 @@ HTML_TEMPLATE = Path(__file__).parent / "melpomene.html"
 HTML_TO_REPLACE = "<!-- your img tags here, see documentation -->"
 
 
-def extract_zooms(src_folder):
+def get_val_has_str(elem: Element, attrib: str, filepath: str | Path) -> str:
+    value = elem.get(attrib)
+
+    if value is None:
+        sys.exit(f"Attribute '{attrib}' is not valid in file {filepath}")
+
+    return str(value)
+
+
+def extract_zooms(src_folder) -> dict[int, Any]:
     folder = Path(src_folder)
 
-    zooms = {}
-
-    max_width = 0
-    max_height = 0
+    pages_zooms: dict[int, Any] = {}
 
     idx = 0
 
@@ -29,44 +35,52 @@ def extract_zooms(src_folder):
 
         print(f"page {idx} : {svg_path.name}")
 
-        zooms[idx] = {
+        # Setting up default values
+        pages_zooms[idx] = {
             "name": svg_path.stem,
             "width": 0,
             "height": 0,
             "zooms": [],
         }
 
-        tree = ET.parse(svg_path)
+        tree = ElementTree.parse(svg_path)
         root = tree.getroot()
 
-        if "." in root.get("width"):
+        width = get_val_has_str(root, "width", svg_path)
+        height = get_val_has_str(root, "height", svg_path)
+
+        if "." in width:
             print(
                 f"WARNING: file {svg_path} has a floating width, it will be rounded",
                 file=sys.stderr,
             )
-        zooms[idx]["width"] = round(float(root.get("width")))
-        if "." in root.get("height"):
+        pages_zooms[idx]["width"] = round(float(width))
+
+        if "." in height:
             print(
                 f"WARNING: file {svg_path} has a floating height, it will be rounded",
                 file=sys.stderr,
             )
-        zooms[idx]["height"] = round(float(root.get("height")))
+        pages_zooms[idx]["height"] = round(float(height))
 
+        zooms = []
         for area in root.findall(".//{*}rect"):
-            zooms[idx]["zooms"].append(
+            zooms.append(
                 [
-                    float(area.get("width")),
-                    float(area.get("height")),
-                    float(area.get("x")),
-                    float(area.get("y")),
+                    float(get_val_has_str(area, "width", svg_path)),
+                    float(get_val_has_str(area, "height", svg_path)),
+                    float(get_val_has_str(area, "x", svg_path)),
+                    float(get_val_has_str(area, "y", svg_path)),
                 ]
             )
 
-    return zooms, max_width, max_height
+        pages_zooms[idx]["zooms"] = zooms
+
+    return pages_zooms
 
 
-def write_json_or_js(zooms, dest_file, is_js):
-    with open(dest_file, "w") as data_file:
+def write_json_or_js(zooms, dest_file, is_js) -> None:
+    with open(dest_file, "w", encoding="UTF-8") as data_file:
         if is_js:
             data_file.write("PAGES_ZOOMS = ")
         data_file.write("[\n")
@@ -75,7 +89,8 @@ def write_json_or_js(zooms, dest_file, is_js):
             for zoom in zooms[page_idx]["zooms"]:
                 if zoom[2] < 0 or zoom[3] < 0:
                     print(
-                        f"WARNING: negative pos x / pos y in page {page_idx} for zoom {zoom} (is the rectangle flipped?)"
+                        f"WARNING: negative pos x / pos y in page {page_idx} for "
+                        f"zoom {zoom} (is the rectangle flipped?)"
                     )
 
                 if first_coma_skiped:
@@ -86,7 +101,7 @@ def write_json_or_js(zooms, dest_file, is_js):
         data_file.write("\n]\n")
 
 
-def write_html(zooms, dest_file, pages_width, pages_height, prefix, extention):
+def write_html(zooms, dest_file, prefix, extention) -> None:
     img_tags = ""
     for page_idx in sorted(zooms.keys()):
         img_url = f"{prefix}{zooms[page_idx]['name']}.{extention}"
@@ -97,22 +112,30 @@ def write_html(zooms, dest_file, pages_width, pages_height, prefix, extention):
         zoom_html_str = ";".join(zoom_html_data)
         img_tags = (
             img_tags
-            + f'            <img loading="lazy" height="{zooms[page_idx]["height"]}" width="{zooms[page_idx]["width"]}" src="{img_url}" data-zooms="{zoom_html_str}"/>\n'
+            + "            "
+            + f'<img loading="lazy" height="{zooms[page_idx]["height"]}" '
+            + f'width="{zooms[page_idx]["width"]}" src="{img_url}" '
+            + f'data-zooms="{zoom_html_str}"/>\n'
         )
 
     img_tags = img_tags.strip()
 
-    with open(HTML_TEMPLATE) as template_file, open(dest_file, "w") as data_file:
+    with open(HTML_TEMPLATE, "r", encoding="UTF-8") as template_file, open(
+        dest_file, "w", encoding="UTF-8"
+    ) as data_file:
         data = template_file.read().replace(HTML_TO_REPLACE, img_tags)
 
         data_file.write(data)
 
 
-def generate_argparse():
+def generate_argparse() -> ArgumentParser:
     """Generate Melpomene's generator input parser"""
 
-    parser = argparse.ArgumentParser(
-        description="Helper that can generate JSON / JS / HTML files for Melpomene webcomic reader"
+    parser = ArgumentParser(
+        description=(
+            "Helper that can generate JSON / JS / "
+            "HTML files for Melpomene webcomic reader"
+        )
     )
 
     parser.add_argument(
@@ -140,7 +163,7 @@ def generate_argparse():
     return parser
 
 
-if __name__ == "__main__":
+def run():
     args = generate_argparse().parse_args()
 
     # Get the final outout name
@@ -160,13 +183,17 @@ if __name__ == "__main__":
     elif args.output_format == "js" and not output.endswith(".js"):
         output += ".js"
 
-    zooms, max_width, max_height = extract_zooms(args.svg_folders)
+    zooms = extract_zooms(args.svg_folders)
 
     if args.output_format == "html":
-        write_html(zooms, output, max_width, max_height, args.p, args.e)
+        write_html(zooms, output, args.p, args.e)
 
     elif args.output_format == "json":
         write_json_or_js(zooms, output, False)
 
     elif args.output_format == "js":
         write_json_or_js(zooms, output, True)
+
+
+if __name__ == "__main__":
+    run()