Index: django_import_export-4.3.7/import_export/command_utils.py
===================================================================
--- django_import_export-4.3.7.orig/import_export/command_utils.py
+++ django_import_export-4.3.7/import_export/command_utils.py
@@ -59,6 +59,8 @@ def get_format_class(format_name, file_n
     else:
         # Determine MIME type from file name
         mimetype, file_encoding = mimetypes.guess_type(file_name)
+        if mimetype == "text/x-comma-separated-values":
+            mimetype = "text/csv"
 
         if not mimetype:
             raise CommandError(