diff --git a/build.vc/mpir_config.py b/build.vc/mpir_config.py
index 96ecb3d7..3cd02581 100644
--- a/build.vc/mpir_config.py
+++ b/build.vc/mpir_config.py
@@ -203,7 +203,7 @@ g2_sym = compile(r'global\s+__g(\w+)')
 def get_symbols(setf, sym_dir):
   for f in setf:
     fn = join(mpir_root_dir, f[2], f[0] + f[1])
-    with open(fn, 'r') as inf:
+    with open(fn, 'r', encoding='utf8', errors='replace') as inf:
       lines = inf.readlines()
       for l in lines:
         m = fr_sym.search(l)
@@ -620,4 +620,4 @@ if debug:
     n, x = splitext(f)
     nd[n] = nd.get(n, []) + [(d, 'asm')]
   for x in nd:
-    print(x, nd[x])
\ No newline at end of file
+    print(x, nd[x])