diff --git a/pyglossary/text_reader.py b/pyglossary/text_reader.py
index 1f63c3b7d..95c8fd1c3 100644
--- a/pyglossary/text_reader.py
+++ b/pyglossary/text_reader.py
@@ -135,10 +135,9 @@ def _open(self, filename: str) -> None:
 		for _ in self._openGen(filename):
 			pass
 
-	def open(self, filename: str) -> Iterator[tuple[int, int]] | None:
+	def open(self, filename: str) -> None:
 		self._filename = filename
 		self._open(filename)
-		return None
 
 	def openGen(self, filename: str) -> Iterator[tuple[int, int]]:
 		"""