diff --git a/run_mypy.py b/run_mypy.py
index 43196fa7f1..66118b36fd 100644
--- a/run_mypy.py
+++ b/run_mypy.py
@@ -1,18 +1,20 @@
-#!env python
+#!/usr/bin/env python
 import os
 import sys
 import subprocess
 
+
 # A quick Python implementation of unix 'where' command.
-def where(exeName, searchPath=os.getenv("PATH")):
-    if searchPath is None:
-        searchPath = ""
-    paths = searchPath.split(";" if sys.platform == "win32" else ":")
+def where(exe_name: str, search_path: str = os.getenv("PATH")) -> str:
+    if search_path is None:
+        search_path = ""
+    paths = search_path.split(";" if sys.platform == "win32" else ":")
     for path in paths:
-        candidatePath = os.path.join(path, exeName)
-        if os.path.exists(candidatePath):
-            return candidatePath
-    return None
+        candidate_path = os.path.join(path, exe_name)
+        if os.path.exists(candidate_path):
+            return candidate_path
+    return ""
+
 
 def findModules(path):
     result = []
@@ -21,6 +23,7 @@ def findModules(path):
             result.append(entry.name)
     return result
 
+
 def main():
     # Find Uranium via the PYTHONPATH var
     uraniumUMPath = where("UM", os.getenv("PYTHONPATH"))
@@ -28,16 +31,16 @@ def main():
         uraniumUMPath = os.path.join("..", "Uranium")
     uraniumPath = os.path.dirname(uraniumUMPath)
 
-    mypyPathParts = [".", os.path.join(".", "plugins"), os.path.join(".", "plugins", "VersionUpgrade"),
-                     uraniumPath, os.path.join(uraniumPath, "stubs")]
+    mypy_path_parts = [".", os.path.join(".", "plugins"), os.path.join(".", "plugins", "VersionUpgrade"),
+                       uraniumPath, os.path.join(uraniumPath, "stubs")]
     if sys.platform == "win32":
-        os.putenv("MYPYPATH", ";".join(mypyPathParts))
+        os.putenv("MYPYPATH", ";".join(mypy_path_parts))
     else:
-        os.putenv("MYPYPATH", ":".join(mypyPathParts))
+        os.putenv("MYPYPATH", ":".join(mypy_path_parts))
 
     # Mypy really needs to be run via its Python script otherwise it can't find its data files.
-    mypyExe = where("mypy.bat" if sys.platform == "win32" else "mypy")
-    mypyModule = os.path.join(os.path.dirname(mypyExe), "mypy")
+    mypy_exe = where("mypy.exe" if sys.platform == "win32" else "mypy")
+    mypy_module = os.path.join(os.path.dirname(mypy_exe), "mypy")
 
     plugins = findModules("plugins")
     plugins.sort()
@@ -46,11 +49,14 @@ def main():
 
     for mod in mods:
         print("------------- Checking module {mod}".format(**locals()))
-        result = subprocess.run([sys.executable, mypyModule, "-p", mod, "--ignore-missing-imports"])
+        result = subprocess.run([sys.executable, mypy_module, "-p", mod, "--ignore-missing-imports"])
         if result.returncode != 0:
             print("\nModule {mod} failed checking. :(".format(**locals()))
             return 1
     else:
         print("\n\nDone checking. All is good.")
     return 0
-sys.exit(main())
+
+
+if __name__ == "__main__":
+    sys.exit(main())