diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0346323..9aa152c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## v2.2.2(2026-01-05)
+
+### Fixed
+
+- Fix a bug in GFM alert block parsing where alert types were case-sensitive.
+- Fix GFM alert regex to disallow content on header line.
+
 ## v2.2.1(2025-10-13)
 
 ### Changed
diff --git a/marko/__init__.py b/marko/__init__.py
index 4aae580..a21e6dd 100644
--- a/marko/__init__.py
+++ b/marko/__init__.py
@@ -23,7 +23,7 @@ if TYPE_CHECKING:
     from .block import Document
     from .parser import ElementType
 
-__version__ = "2.2.1"
+__version__ = "2.2.2"
 
 
 class SetupDone(Exception):
diff --git a/marko/ext/gfm/elements.py b/marko/ext/gfm/elements.py
index fa98289..2edcaeb 100644
--- a/marko/ext/gfm/elements.py
+++ b/marko/ext/gfm/elements.py
@@ -225,11 +225,13 @@ class Alert(block.Quote):
 
     @classmethod
     def match(cls, source):
-        return source.expect_re(r" {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]")
+        return source.expect_re(
+            r"(?im) {,3}>\s*\[\!(WARNING|NOTE|TIP|IMPORTANT|CAUTION)\]\s*$"
+        )
 
     @classmethod
     def parse(cls, source):
-        alert_type = source.match.group(1)
+        alert_type = source.match.group(1).upper()
         source.next_line(require_prefix=False)
         source.consume()
         state = cls(alert_type)