diff --git a/ffi/build.py b/ffi/build.py
index 3889ba5..58f93ec 100755
--- a/ffi/build.py
+++ b/ffi/build.py
@@ -58,7 +58,7 @@ def find_win32_generator():
 
 def main_win32():
     generator = find_win32_generator()
-    config = 'Release'
+    config = 'Debug'
     if not os.path.exists(build_dir):
         os.mkdir(build_dir)
     try_cmake(here_dir, build_dir, generator)