diff --git a/.gitignore b/.gitignore
index 7675281..c99f8a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,12 @@
 *
 
+!build/
+!build/example/
+
 !example/
 
 !.gitignore
 
 !*.html
 !*.md
-!*.sh
+!*.py
diff --git a/README.md b/README.md
index fa5bf2a..a7f5b11 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ Preprocess HTML files with the C processor.
 Simply run the build script:
 
 ```sh
-./build.sh
+./build.py
 ```
 
 And you will get your compiled HTML files in the `build` directory.
diff --git a/build.py b/build.py
new file mode 100755
index 0000000..a7dad4e
--- /dev/null
+++ b/build.py
@@ -0,0 +1,97 @@
+#!/usr/bin/env python
+import os
+import shutil
+import subprocess as spc
+from pathlib import Path
+
+PWD = Path(".")
+BUILD_DIR = Path("build")
+
+IGNORE_DIRS = [
+    ".idea",
+    "build",
+    "venv",
+]
+
+# If a file extension is here and the key value is True, it will get processed.
+# If it is here and the key value is False, it will get copied.
+TO_PROCESS = {
+    "html": True,
+    "css": False,
+    "ico": False,
+    "js": False,
+    "png": False,
+    "svg": False,
+    "webmanifest": False,
+    "xml": False,
+}
+
+
+def ext_of(file: Path) -> str:
+    """Returns the extension of the given file."""
+    return file.name.split(".")[-1]
+
+
+def should_process(file: Path) -> bool:
+    """Returns whether if the file should be processed."""
+    return should_copy(file) and TO_PROCESS.get(ext_of(file), False)
+
+
+def should_copy(file: Path, /) -> bool:
+    """Returns whether if the file should be copied (i.e. included in the build/ dir)."""
+    return ext_of(file) in TO_PROCESS and not file.name.startswith("_")
+
+
+def process_file(in_: Path, out: Path, /) -> None:
+    """
+    Processes the give file with the C preprocessor.
+    Writes the output to the given file.
+    Filters lines that start with `#`.
+    """
+    process = spc.Popen(
+        f"cc -E - < {in_}", stderr=spc.DEVNULL, stdout=spc.PIPE, shell=True
+    )
+
+    with out.open("wb") as out_file:
+        for line in process.stdout:
+            if line.startswith(b"#"):
+                continue
+
+            out_file.write(line)
+
+
+def build(directory: Path, /) -> None:
+    for path in directory.iterdir():
+        if any(
+            part in IGNORE_DIRS
+            for part in (path.parts[:-1] if path.is_file() else path.parts)
+        ):
+            continue
+
+        if path.is_dir():
+            build(path)
+            continue
+
+        if not should_copy(path):
+            continue
+
+        path_build_path = BUILD_DIR / path.relative_to(PWD)
+        path_build_path.parent.mkdir(parents=True, exist_ok=True)
+
+        if should_process(path):
+            print("Building", end="")
+            process_file(path, path_build_path)
+        else:
+            print("Copying ", end="")
+            shutil.copyfile(path, path_build_path)
+
+        print(f" {path}...")
+
+
+if __name__ == "__main__":
+    shutil.rmtree("build", ignore_errors=True)
+    os.makedirs("build")
+
+    build(PWD)
+    print()
+    print("Building finished!")
diff --git a/build.sh b/build.sh
deleted file mode 100755
index 19ab826..0000000
--- a/build.sh
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/bin/sh
-
-function process {
-  cc -E - < "$1"
-}
-
-rm -rf ./build
-mkdir ./build
-
-for html_file in $(find -name "*.html"); do
-  path=./build/${html_file#./}
-
-  # Preprocess if filename doesn't start with _.
-  if [[ $(basename $html_file) != _* ]]; then
-    echo "Building $html_file..."
-    mkdir $(dirname $path) 2> /dev/null
-    sed "/^#/d" <(process $html_file) > $path
-  fi
-done