diff --git a/setup.py b/setup.py
index 3369f937..54add25f 100644
--- a/setup.py
+++ b/setup.py
@@ -1,38 +1,134 @@
+from pathlib import Path
 from setuptools import setup, Extension
 import subprocess
+import json
 import shlex
-import glob
 import sys
 import os
 
 
-compiler_options = {"unix": ["-mavx2"], "msvc": ["/arch:AVX2"]}
-
-compiler_type = "msvc" if os.name == "nt" else "unix"
+extra_compiler_options = []
 
+if sys.platform == "linux" or sys.platform == "linux2":
+    extra_compiler_options.append("-mavx2")
+elif sys.platform == "win32":
+    extra_compiler_options.append("/arch:AVX2")
+elif sys.platform == "darwin":
+    pass
 
 extensions = [
     Extension(
         "geometry",
         sources=["src_c/geometry.c"],
-        extra_compile_args=compiler_options[compiler_type],
+        extra_compile_args=extra_compiler_options,
     )
 ]
 
 
+def consume_arg(arg: str) -> bool:
+    if arg in sys.argv:
+        sys.argv.remove(arg)
+        return True
+    return False
+
+
+def get_geometry_cache_dir() -> Path:
+    path = Path("./__geometry_cache__")
+
+    path.mkdir(exist_ok=True)
+
+    return path
+
+
+def get_times_json_file() -> Path:
+    path = get_geometry_cache_dir() / "times.json"
+
+    path.touch(exist_ok=True)
+
+    return path
+
+
+def update_times_file() -> None:
+    files = list(Path("./src_c/").glob("**/*.[c|h]"))
+
+    data: Dict[str, float] = {str(file): os.path.getmtime(str(file)) for file in files}
+
+    with open(get_times_json_file(), "w") as f:
+        f.truncate(0)
+        f.write(json.dumps(data, indent=4))
+
+
+def needs_to_be_rebuild() -> bool:
+    files = list(Path("./src_c/").glob("**/*.[c|h]"))
+
+    with open(get_times_json_file(), "r+") as f:
+        file_contents = f.read()
+        data: Dict[str, float]
+
+        if file_contents == "":
+            data = {}
+        else:
+            data = json.loads(file_contents)
+
+        if not data:
+            for file in files:
+                data[str(file)] = os.path.getmtime(str(file))
+
+            f.write(json.dumps(data, indent=4))
+
+            return True
+
+        result = False
+
+        for file in files:
+            if data[str(file)] != os.path.getmtime(str(file)):
+                data[str(file)] = os.path.getmtime(str(file))
+                result = True
+
+    with open(get_times_json_file(), "w") as f:
+        f.truncate(0)
+        f.write(json.dumps(data, indent=4))
+
+    return result
+
+
 def build() -> None:
+    if not needs_to_be_rebuild():
+        print("latest version of geometry already built")
+        return
+    print("building latest version of geometry...")
+
+    with open("src_c/geometry.c", "r+") as f:
+        original_geometry_c = f.read()
+        f.write(" ")
+
     setup(
         name="geometry",
         ext_modules=extensions,
     )
 
+    with open("src_c/geometry.c", "w") as f:
+        f.truncate(0)
+        f.write(original_geometry_c)
+
+    update_times_file()
+
 
 if __name__ == "__main__":
-    if "format" in sys.argv:
-        c_files = glob.glob("src_c/*.c")
-        h_files = glob.glob("src_c/include/*.h")
+    for arg in sys.argv:
+        if arg in ("--format", "install", "--test"):
+            break
+    else:
+        setup(
+            name="geometry",
+            ext_modules=extensions,
+        )
+        sys.exit(0)
 
-        cmd = ["clang-format", "-i"] + c_files + h_files
+    if consume_arg("--format"):
+        cmd = ["clang-format", "-i"] + [
+            str(file) for file in Path("./src_c/").glob("**/*.[c|h]")
+        ]
         print(shlex.join(cmd))
         subprocess.call(cmd)
 
@@ -40,6 +136,11 @@ def build() -> None:
         print(shlex.join(cmd))
         subprocess.call(cmd)
 
-        sys.exit(0)
+    run_tests = consume_arg("--test")
 
     build()
+
+    if run_tests:
+        cmd = ["python", "-m", "unittest"]
+        print(shlex.join(cmd))
+        subprocess.call(cmd)