diff --git a/git/refs/symbolic.py b/git/refs/symbolic.py
index 0c0fa4045..1c5506737 100644
--- a/git/refs/symbolic.py
+++ b/git/refs/symbolic.py
@@ -352,7 +352,7 @@ def set_reference(self, ref: Union[Commit_ish, 'SymbolicReference', str],
         fd = lfd.open(write=True, stream=True)
         ok = True
         try:
-            fd.write(write_value.encode('ascii') + b'\n')
+            fd.write(write_value.encode('utf-8') + b'\n')
             lfd.commit()
             ok = True
         finally: