diff --git a/src/flake8/defaults.py b/src/flake8/defaults.py
index 3fff376..72452a7 100644
--- a/src/flake8/defaults.py
+++ b/src/flake8/defaults.py
@@ -36,7 +36,7 @@ NOQA_INLINE_REGEXP = re.compile(
     # We do not care about the casing of ``noqa``
     # We want a comma-separated list of errors
     # https://regex101.com/r/4XUuax/2 full explenation of the regex
-    r"# noqa(?::[\s]?(?P<codes>([A-Z][0-9]+(?:[,\s]+)?)+))?",
+    r"# noqa(?::[\s]?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?",
     re.IGNORECASE,
 )
 
diff --git a/tests/unit/test_violation.py b/tests/unit/test_violation.py
index e29d874..a3a56f0 100644
--- a/tests/unit/test_violation.py
+++ b/tests/unit/test_violation.py
@@ -23,6 +23,9 @@ from flake8 import style_guide
     ('E111', 'a = 1  # noqa - We do not care', True),
     ('E111', 'a = 1  # noqa: We do not care', True),
     ('E111', 'a = 1  # noqa:We do not care', True),
+    ('ABC123', 'a = 1  # noqa: ABC123', True),
+    ('E111', 'a = 1  # noqa: ABC123', False),
+    ('ABC123', 'a = 1  # noqa: ABC124', False),
 ])
 def test_is_inline_ignored(error_code, physical_line, expected_result):
     """Verify that we detect inline usage of ``# noqa``."""