diff --git a/changelogs/client_server/newsfragments/1564.clarification b/changelogs/client_server/newsfragments/1564.clarification
new file mode 100644
index 00000000..59fcf699
--- /dev/null
+++ b/changelogs/client_server/newsfragments/1564.clarification
@@ -0,0 +1 @@
+Allow `null` in `room_types` in `POST /publicRooms` endpoints schemas.
diff --git a/changelogs/server_server/newsfragments/1564.clarification b/changelogs/server_server/newsfragments/1564.clarification
new file mode 100644
index 00000000..59fcf699
--- /dev/null
+++ b/changelogs/server_server/newsfragments/1564.clarification
@@ -0,0 +1 @@
+Allow `null` in `room_types` in `POST /publicRooms` endpoints schemas.
diff --git a/data/api/client-server/list_public_rooms.yaml b/data/api/client-server/list_public_rooms.yaml
index e4f0551b..ba816b06 100644
--- a/data/api/client-server/list_public_rooms.yaml
+++ b/data/api/client-server/list_public_rooms.yaml
@@ -214,7 +214,7 @@ paths:
                       type: array
                       x-addedInMatrixVersion: "1.4"
                       items:
-                        type: string
+                        type: ["string", "null"]
                       description: |-
                         An optional list of [room types](/client-server-api/#types) to search
                         for. To include rooms without a room type, specify `null` within this
diff --git a/data/api/server-server/public_rooms.yaml b/data/api/server-server/public_rooms.yaml
index dd909f8f..c81789ae 100644
--- a/data/api/server-server/public_rooms.yaml
+++ b/data/api/server-server/public_rooms.yaml
@@ -107,7 +107,7 @@ paths:
                       type: array
                       x-addedInMatrixVersion: "1.4"
                       items:
-                        type: string
+                        type: ["string", "null"]
                       description: |-
                         An optional list of [room types](/client-server-api/#types) to search
                         for. To include rooms without a room type, specify `null` within this
diff --git a/layouts/partials/openapi/render-object-table.html b/layouts/partials/openapi/render-object-table.html
index 5c38be87..4fc5ac76 100644
--- a/layouts/partials/openapi/render-object-table.html
+++ b/layouts/partials/openapi/render-object-table.html
@@ -102,11 +102,24 @@
             internal structure, handle this with a bit of recursion
         */}}
         {{ $type = delimit (slice "{string: " (partial "type-or-title" .additionalProperties) "}" ) "" }}
-    {{ else if and .oneOf (reflect.IsSlice .oneOf) }}
+    {{ else if reflect.IsSlice .type }}
         {{/* It's legal to specify an array of types. Join them together in that case */}}
 
         {{ $types := slice }}
 
+        {{ range .type }}
+            {{ $types = $types | append . }}
+        {{ end }}
+
+        {{ $type = delimit $types "|" }}
+    {{ else if and .oneOf (reflect.IsSlice .oneOf) }}
+        {{/*
+            This is like an array of types except some of the types probably have a schema.
+            Join them together too.
+        */}}
+
+        {{ $types := slice }}
+
         {{ range .oneOf }}
             {{ $types = $types | append .type }}
         {{ end }}