diff --git a/pystream/models/squire.py b/pystream/models/squire.py
index a36bed5..6e9d9ad 100644
--- a/pystream/models/squire.py
+++ b/pystream/models/squire.py
@@ -97,8 +97,11 @@ def get_iter(filename: pathlib.PurePath) -> Union[Tuple[str, str], Tuple[None, N
         Tuple[str, str]:
         Tuple of previous file and next file.
     """
-    dir_content = sorted((file for file in os.listdir(filename.parent) if pathlib.PosixPath(file).suffix in config.env.file_formats),
-                         key=lambda x: natural_sort_key(x))
+    # Extract only the file formats that are supported
+    dir_content = sorted(
+        (file for file in os.listdir(filename.parent) if pathlib.PosixPath(file).suffix in config.env.file_formats),
+        key=lambda x: natural_sort_key(x)
+    )
     idx = dir_content.index(filename.name)
     try:
         previous_ = dir_content[idx - 1]