diff --git a/buildtap.py b/buildtap.py
index 78f9587..4b81891 100644
--- a/buildtap.py
+++ b/buildtap.py
@@ -186,9 +186,9 @@ def repfn(m):
             return kv.get(var, '')
         if out_path is None:
             out_path = in_path
-        with open(in_path+'.in') as f:
+        with open(in_path+'.in', encoding='utf_8_sig') as f:
             modtxt = re.sub(self.macro_amper, repfn, f.read())
-        with open(out_path, "w") as f:
+        with open(out_path, "w", encoding='utf_8_sig') as f:
             f.write(modtxt)
 
     # set up configuration files for building tap driver