diff --git a/src/blib2to3/pgen2/pgen.py b/src/blib2to3/pgen2/pgen.py
index 17f7533..ea6d8cc 100644
--- a/src/blib2to3/pgen2/pgen.py
+++ b/src/blib2to3/pgen2/pgen.py
@@ -357,7 +357,9 @@ def raise_error(self, msg: str, *args: Any) -> NoReturn:
                 msg = msg % args
             except Exception:
                 msg = " ".join([msg] + list(map(str, args)))
-        raise SyntaxError(msg, (self.filename, self.end[0], self.end[1], self.line))
+        raise SyntaxError(
+            msg, (str(self.filename), self.end[0], self.end[1], self.line)
+        )
 
 
 class NFAState: