diff --git a/changelog.d/7780.misc b/changelog.d/7780.misc
new file mode 100644
index 000000000..a627bea45
--- /dev/null
+++ b/changelog.d/7780.misc
@@ -0,0 +1 @@
+Allow to use higher versions of prometheus_client <0.9.0 which are expected to introduce no breaking changes. Contributed by Oliver Kurz.
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index b1cac901e..8cfcdb057 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -66,7 +66,7 @@ REQUIREMENTS = [
     "pymacaroons>=0.13.0",
     "msgpack>=0.5.2",
     "phonenumbers>=8.2.0",
-    "prometheus_client>=0.0.18,<0.8.0",
+    "prometheus_client>=0.0.18,<0.9.0",
     # we use attr.validators.deep_iterable, which arrived in 19.1.0
     "attrs>=19.1.0",
     "netaddr>=0.7.18",