diff --git a/pyproject.toml b/pyproject.toml
index 2d0f25a78..ee290f0e6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -51,7 +51,7 @@ joblib = ">=1.0.1"
 jsonpath-ng = ">=1.5.3"
 jsonschema = ">=4.16.0"
 memoization = { version = ">=0.3.2,<0.5.0", python = "<4" }
-msgspec = "^0.18.6"
+msgspec = ">=0.18,<0.19"
 packaging = ">=23.1"
 pendulum = ">=2.1.0,<4"
 PyJWT = "~=2.4"
diff --git a/singer_sdk/mapper_base.py b/singer_sdk/mapper_base.py
index 337f68635..9582c0dbf 100644
--- a/singer_sdk/mapper_base.py
+++ b/singer_sdk/mapper_base.py
@@ -112,7 +112,7 @@ def invoke(  # type: ignore[override]
         about: bool = False,
         about_format: str | None = None,
         config: tuple[str, ...] = (),
-        file_input: t.BinaryIO | None = None,
+        file_input: t.IO[bytes] | None = None,
     ) -> None:
         """Invoke the mapper.
 
diff --git a/singer_sdk/target_base.py b/singer_sdk/target_base.py
index 7992711b5..1255b6cbf 100644
--- a/singer_sdk/target_base.py
+++ b/singer_sdk/target_base.py
@@ -540,7 +540,7 @@ def invoke(  # type: ignore[override]
         about: bool = False,
         about_format: str | None = None,
         config: tuple[str, ...] = (),
-        file_input: t.BinaryIO | None = None,
+        file_input: t.IO[bytes] | None = None,
     ) -> None:
         """Invoke the target.