diff --git a/lbrynet/core/Wallet.py b/lbrynet/core/Wallet.py
index 4e54fd58c..6770faca4 100644
--- a/lbrynet/core/Wallet.py
+++ b/lbrynet/core/Wallet.py
@@ -125,7 +125,7 @@ class Wallet(object):
                 s3_height = (len(raw_headers) / HEADER_SIZE) - 1
                 local_height = self.local_header_file_height()
                 if s3_height > local_height:
-                    with open(os.path.join(self.config.path, "blockchain_headers"), "w") as headers_file:
+                    with open(os.path.join(self.config.path, "blockchain_headers"), "wb") as headers_file:
                         headers_file.write(raw_headers)
                     log.info("fetched headers from s3 (s3 height: %i)", s3_height)
                 else: