diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a96696ac..59aa19bd 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -514,7 +514,7 @@ jobs:
             ./interop/python/radix_engine_toolkit/x86_64-unknown-linux-gnu
           cp \
             ./artifacts/radix-engine-toolkit-uniffi-x86_64-pc-windows-gnu/radix_engine_toolkit_uniffi.dll \
-            ./interop/python/radix_engine_toolkit/x86_64-pc-windows-gnu
+            ./interop/python/radix_engine_toolkit/x86_64-pc-windows-gnu.dll
       - name: Build Package
         working-directory: ./interop/python/
         run: python3 -m build --wheel
diff --git a/interop/python/replacement.py b/interop/python/replacement.py
index 4ef00dba..b6ae62ec 100644
--- a/interop/python/replacement.py
+++ b/interop/python/replacement.py
@@ -30,7 +30,10 @@ def library_file_name() -> str:
         elif is_arm and system == "Linux":
             return "aarch64-unknown-linux-gnu"
         elif is_x86 and system == "Windows":
-            return "x86_64-pc-windows-gnu"
+            # Either Windows or the Python runtime on Windows requires that DLLs
+            # have an extension of `.dll`. This is why this is the only dynamic
+            # library with an extension.
+            return "x86_64-pc-windows-gnu.dll"
         else:
             raise NotImplemented(f"No implementation of the Radix Engine Toolkit is available on your platform. Information detected: is_x86: {is_x86}, is_arm: {is_arm}, os: {system}")
 
diff --git a/interop/python/setup.py b/interop/python/setup.py
index 11cac23c..25836dbe 100644
--- a/interop/python/setup.py
+++ b/interop/python/setup.py
@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="radix-engine-toolkit",
-    version="1.0.0rc2",
+    version="1.0.0rc3",
     packages=["radix_engine_toolkit"],
     author="radixdlt",
     description="A Python wrapper around the Radix Engine Toolkit that provides Radix Ledger primitives to Python.",
@@ -24,7 +24,7 @@
             "aarch64-apple-darwin",
             "aarch64-unknown-linux-gnu",
             "x86_64-apple-darwin",
-            "x86_64-pc-windows-gnu",
+            "x86_64-pc-windows-gnu.dll",
             "x86_64-unknown-linux-gnu",
         ]
     },