diff --git a/pylib/gyp/common.py b/pylib/gyp/common.py
index 3f2329bd..bfe546f8 100644
--- a/pylib/gyp/common.py
+++ b/pylib/gyp/common.py
@@ -364,7 +364,7 @@ def __init__(self):
                 dir=base_temp_dir,
             )
             try:
-                self.tmp_file = os.fdopen(tmp_fd, "w")
+                self.tmp_file = os.fdopen(tmp_fd, "wb")
             except Exception:
                 # Don't leave turds behind.
                 os.unlink(self.tmp_path)