diff --git a/changelogs/client_server/newsfragments/1323.clarification b/changelogs/client_server/newsfragments/1323.clarification
new file mode 100644
index 000000000..9155786d5
--- /dev/null
+++ b/changelogs/client_server/newsfragments/1323.clarification
@@ -0,0 +1 @@
+Require request field `refresh_token` at endpoint `POST /_matrix/client/v3/refresh`.
\ No newline at end of file
diff --git a/data/api/client-server/refresh.yaml b/data/api/client-server/refresh.yaml
index da34070c4..5923d3b72 100644
--- a/data/api/client-server/refresh.yaml
+++ b/data/api/client-server/refresh.yaml
@@ -61,6 +61,8 @@ paths:
               refresh_token:
                 type: string
                 description: The refresh token
+            required:
+              - refresh_token
       responses:
         200:
           description: A new access token and refresh token were generated.