diff --git a/src/udar/sentence.py b/src/udar/sentence.py
index 8489ba8..67fbf4a 100644
--- a/src/udar/sentence.py
+++ b/src/udar/sentence.py
@@ -489,7 +489,7 @@ def disambiguate(self, gram_path: Union[str, Path] = '',
         else:
             cmd = ['vislcg3', '-g', gram_path]
         try:
-            p = Popen(cmd, stdin=PIPE, stdout=PIPE, universal_newlines=True)
+            p = Popen(cmd, encoding='utf8', stdin=PIPE, stdout=PIPE, universal_newlines=True)
         except FileNotFoundError as e:
             raise FileNotFoundError('vislcg3 must be installed and be in your '
                                     'PATH variable to disambiguate a text.') from e  # noqa: E501