diff --git a/src/flake8/defaults.py b/src/flake8/defaults.py
index ec68067..22304a9 100644
--- a/src/flake8/defaults.py
+++ b/src/flake8/defaults.py
@@ -28,12 +28,15 @@ NOQA_INLINE_REGEXP = re.compile(
     # ``# noqa``
     # ``# noqa: E123``
     # ``# noqa: E123,W451,F921``
+    # ``# noqa:E123,W451,F921``
     # ``# NoQA: E123,W451,F921``
     # ``# NOQA: E123,W451,F921``
+    # ``# NOQA: E123,W451,F921``
     # We do not want to capture the ``: `` that follows ``noqa``
     # We do not care about the casing of ``noqa``
     # We want a comma-separated list of errors
-    r"# noqa(?:: (?P<codes>([A-Z][0-9]+(?:[,\s]+)?)+))?",
+    # https://regex101.com/r/4XUuax/2 full explenation of the regex
+    r"# noqa(?::[\s]?(?P<codes>([A-Z][0-9]+(?:[,\s]+)?)+))?",
     re.IGNORECASE,
 )
 
diff --git a/tests/unit/test_file_processor.py b/tests/unit/test_file_processor.py
index 0c2dc99..7d64f6e 100644
--- a/tests/unit/test_file_processor.py
+++ b/tests/unit/test_file_processor.py
@@ -69,9 +69,13 @@ def test_strip_utf_bom(first_line):
     ([u'\uFEFF"""Module docstring."""\n'], False),
     (['#!/usr/bin/python', '# flake8 is great', 'a = 1'], False),
     (['#!/usr/bin/python', '# flake8: noqa', 'a = 1'], True),
+    (['#!/usr/bin/python', '# flake8:noqa', 'a = 1'], True),
     (['# flake8: noqa', '#!/usr/bin/python', 'a = 1'], True),
+    (['# flake8:noqa', '#!/usr/bin/python', 'a = 1'], True),
     (['#!/usr/bin/python', 'a = 1', '# flake8: noqa'], True),
+    (['#!/usr/bin/python', 'a = 1', '# flake8:noqa'], True),
     (['#!/usr/bin/python', 'a = 1  # flake8: noqa'], False),
+    (['#!/usr/bin/python', 'a = 1  # flake8:noqa'], False),
 ])
 def test_should_ignore_file(lines, expected):
     """Verify that we ignore a file if told to."""
diff --git a/tests/unit/test_violation.py b/tests/unit/test_violation.py
index c4b56b1..e29d874 100644
--- a/tests/unit/test_violation.py
+++ b/tests/unit/test_violation.py
@@ -13,10 +13,16 @@ from flake8 import style_guide
     ('W123', 'a = 1  # noqa: E111,W123,F821', True),
     ('W123', 'a = 1  # noqa: E111, W123,F821', True),
     ('E111', 'a = 1  # noqa: E11,W123,F821', True),
+    ('E121', 'a = 1  # noqa:E111,W123,F821', False),
+    ('E111', 'a = 1  # noqa:E111,W123,F821', True),
+    ('W123', 'a = 1  # noqa:E111,W123,F821', True),
+    ('W123', 'a = 1  # noqa:E111, W123,F821', True),
+    ('E111', 'a = 1  # noqa:E11,W123,F821', True),
     ('E111', 'a = 1  # noqa, analysis:ignore', True),
     ('E111', 'a = 1  # noqa analysis:ignore', True),
     ('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),
 ])
 def test_is_inline_ignored(error_code, physical_line, expected_result):
     """Verify that we detect inline usage of ``# noqa``."""