diff --git a/whatformat/util/whatdateformat.py b/whatformat/util/whatdateformat.py
index e069bcb4012fc2be783a52258a0858c9fa318173..0b39f321279fb7f5c95093e1cf7ca65e16bfd784 100644
--- a/whatformat/util/whatdateformat.py
+++ b/whatformat/util/whatdateformat.py
@@ -25,7 +25,6 @@ def _get_all_format_strings(date_string, allow_reuse=False,
     try:
         parsed_datetime = parse(date_string)
     except ParserError:
-        yield ''
         return
     tokens = DATE_TOKEN_REGEX.findall(date_string)
     possible_matches = defaultdict(list)  # type: Dict[str, List[str]]