diff --git a/studio/backend/main.py b/studio/backend/main.py
index 65f5e7fe90..67908d8617 100644
--- a/studio/backend/main.py
+++ b/studio/backend/main.py
@@ -23,10 +23,23 @@ if _backend_dir not in sys.path:
 # See: https://github.com/python/cpython/issues/102396
 import _platform_compat  # noqa: F401
 
+import mimetypes
 import shutil
 import warnings
 from contextlib import asynccontextmanager
 
+# Fix broken Windows registry MIME types.  Some Windows installs map .js to
+# "text/plain" in the registry (HKCR\.js\Content Type).  Python's mimetypes
+# module reads from the registry, and FastAPI/Starlette's StaticFiles uses
+# mimetypes.guess_type() to set Content-Type headers.  Browsers enforce strict
+# MIME checking for ES module scripts (<script type="module">) and will refuse
+# to execute .js files served as text/plain — resulting in a blank page.
+# Calling add_type() *before* StaticFiles is instantiated ensures the correct
+# types are used regardless of the OS registry.
+if sys.platform == "win32":
+    mimetypes.add_type("application/javascript", ".js")
+    mimetypes.add_type("text/css", ".css")
+
 # Suppress annoying dependency warnings in production
 if os.getenv("ENVIRONMENT_TYPE", "production") == "production":
     warnings.filterwarnings("ignore")