diff --git a/src/syrupy/extensions/single_file.py b/src/syrupy/extensions/single_file.py
index f6739a7e..4af378fc 100644
--- a/src/syrupy/extensions/single_file.py
+++ b/src/syrupy/extensions/single_file.py
@@ -30,7 +30,7 @@ def serialize(
         *,
         exclude: Optional["PropertyFilter"] = None,
         matcher: Optional["PropertyMatcher"] = None,
-    ) -> SerializedData:
+    ) -> "SerializedData":
         return bytes(data)
 
     def get_snapshot_name(self, *, index: int = 0) -> str: