diff --git a/changelog.d/11439.bugfix b/changelog.d/11439.bugfix
new file mode 100644
index 000000000..fc6bc82b3
--- /dev/null
+++ b/changelog.d/11439.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in 1.47.0 where `send_join` could fail due to an outdated `ijson` version.
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 154e5b702..7d2695424 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -86,7 +86,7 @@ REQUIREMENTS = [
     # We enforce that we have a `cryptography` version that bundles an `openssl`
     # with the latest security patches.
     "cryptography>=3.4.7",
-    "ijson>=3.0",
+    "ijson>=3.1",
 ]
 
 CONDITIONAL_REQUIREMENTS = {