github_url="https://github.com/ytdl-org/youtube-dl"
buggy_commit_id="435e382423f860aca82a58d7c3db58cbfa242b40"
fixed_commit_id ="e118a8794ffe5a3a414afd489726f34d753b0b23"
test_file="test/test_YoutubeDL.py"
test_command="python -m unittest -q test.test_YoutubeDL.TestFormatSelection.test_format_selection_string_ops"


diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index a827414dc..80ed8d7e5 100755
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -1078,7 +1078,7 @@ class YoutubeDL(object):
                 comparison_value = m.group('value')
                 str_op = STR_OPERATORS[m.group('op')]
                 if m.group('negation'):
-                    op = lambda attr, value: not str_op
+                    op = lambda attr, value: not str_op(attr, value)
                 else:
                     op = str_op