diff --git a/configure.py b/configure.py
index b7459181..73d1af0d 100755
--- a/configure.py
+++ b/configure.py
@@ -103,6 +103,8 @@
   cmake_cmd += [f"-DCMAKE_TOOLCHAIN_FILE={cmake_toolchain_file}"]
   with cmake_toolchain_file.open("w") as f:
     print(textwrap.dedent(f"""\
+      set(CMAKE_SYSTEM_NAME "Windows")
+
       set(CMAKE_C_COMPILER "{cl_path}")
       set(CMAKE_CXX_COMPILER "{cl_path}")
       set(CMAKE_RC_COMPILER "{rc_path}")