diff --git a/CHANGES/6550.misc b/CHANGES/6550.misc
new file mode 100644
index 00000000000..db8cae6a468
--- /dev/null
+++ b/CHANGES/6550.misc
@@ -0,0 +1 @@
+Pin multidict<6, due to possible regressions.
diff --git a/setup.cfg b/setup.cfg
index 6adc74be6db..8f4b3bf8cc6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -50,7 +50,7 @@ include_package_data = True
 install_requires =
   attrs >= 17.3.0
   charset-normalizer >=2.0, < 3.0
-  multidict >=4.5, < 7.0
+  multidict >=4.5, < 6.0
   async_timeout >= 4.0.0a3, < 5.0
   asynctest == 0.13.0; python_version<"3.8"
   yarl >= 1.0, < 2.0