diff --git a/CHANGES.md b/CHANGES.md
index 6618378c06..05ca83df5d 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,14 @@
+Synapse 1.55.1 (2022-03-24)
+===========================
+
+This is a patch release that fixes an incompatibility with version 3.1.0 of the [Jinja](https://pypi.org/project/Jinja2/) library, released on March 24th, 2022. Deployments of Synapse using the `matrixdotorg/synapse` Docker image or Debian packages from packages.matrix.org are not affected.
+
+Internal Changes
+----------------
+
+- Remove uses of the long-deprecated `jinja2.Markup` which would prevent Synapse from starting with Jinja 3.1.0 or above installed. ([\#12289](https://github.com/matrix-org/synapse/issues/12289))
+
+
 Synapse 1.55.0 (2022-03-22)
 ===========================
 
diff --git a/debian/changelog b/debian/changelog
index 7eed6c5b4a..f3ac279302 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+matrix-synapse-py3 (1.55.1) stable; urgency=medium
+
+  * New synapse release 1.55.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Thu, 24 Mar 2022 17:44:23 +0000
+
 matrix-synapse-py3 (1.55.0) stable; urgency=medium
 
   * New synapse release 1.55.0.
diff --git a/synapse/__init__.py b/synapse/__init__.py
index f0f224d0bb..70f56824f9 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -68,7 +68,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.55.0"
+__version__ = "1.55.1"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 649a4f49d0..5ccdd88364 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -18,6 +18,7 @@ from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, TypeVar
 
 import bleach
 import jinja2
+from markupsafe import Markup
 
 from synapse.api.constants import EventTypes, Membership, RoomTypes
 from synapse.api.errors import StoreError
@@ -867,7 +868,7 @@ class Mailer:
         )
 
 
-def safe_markup(raw_html: str) -> jinja2.Markup:
+def safe_markup(raw_html: str) -> Markup:
     """
     Sanitise a raw HTML string to a set of allowed tags and attributes, and linkify any bare URLs.
 
@@ -877,7 +878,7 @@ def safe_markup(raw_html: str) -> jinja2.Markup:
     Returns:
         A Markup object ready to safely use in a Jinja template.
     """
-    return jinja2.Markup(
+    return Markup(
         bleach.linkify(
             bleach.clean(
                 raw_html,
@@ -891,7 +892,7 @@ def safe_markup(raw_html: str) -> jinja2.Markup:
     )
 
 
-def safe_text(raw_text: str) -> jinja2.Markup:
+def safe_text(raw_text: str) -> Markup:
     """
     Sanitise text (escape any HTML tags), and then linkify any bare URLs.
 
@@ -901,7 +902,7 @@ def safe_text(raw_text: str) -> jinja2.Markup:
     Returns:
         A Markup object ready to safely use in a Jinja template.
     """
-    return jinja2.Markup(
+    return Markup(
         bleach.linkify(bleach.clean(raw_text, tags=[], attributes=[], strip=False))
     )
 
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 1dd39f06cf..232f9a9595 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -75,6 +75,7 @@ REQUIREMENTS = [
     "attrs>=19.2.0,!=21.1.0",
     "netaddr>=0.7.18",
     "Jinja2>=2.9",
+    "MarkupSafe>=2.0",
     "bleach>=1.4.3",
     # We use `ParamSpec`, which was added in `typing-extensions` 3.10.0.0.
     "typing-extensions>=3.10.0",