diff --git a/pywidevine/pssh.py b/pywidevine/pssh.py
index 9e978cb..aac9961 100644
--- a/pywidevine/pssh.py
+++ b/pywidevine/pssh.py
@@ -108,13 +108,11 @@ class PSSH:
         flags: int = 0
     ) -> PSSH:
         """Craft a new version 0 or 1 PSSH Box."""
-        if key_ids is not None:
-            if not isinstance(key_ids, list):
-                raise TypeError(f"Expected key_ids to be a list not {key_ids!r}")
+        if key_ids is not None and not isinstance(key_ids, list):
+            raise TypeError(f"Expected key_ids to be a list not {key_ids!r}")
 
-        if init_data is not None:
-            if not isinstance(init_data, (WidevinePsshData, str, bytes)):
-                raise TypeError(f"Expected init_data to be a {WidevinePsshData}, base64, or bytes, not {init_data!r}")
+        if init_data is not None and not isinstance(init_data, (WidevinePsshData, str, bytes)):
+            raise TypeError(f"Expected init_data to be a {WidevinePsshData}, base64, or bytes, not {init_data!r}")
 
         if not isinstance(version, int):
             raise TypeError(f"Expected version to be an int not {version!r}")