diff --git a/changelogs/client_server/newsfragments/1455.clarification b/changelogs/client_server/newsfragments/1455.clarification
new file mode 100644
index 00000000..3ccb2333
--- /dev/null
+++ b/changelogs/client_server/newsfragments/1455.clarification
@@ -0,0 +1 @@
+Fix various typos throughout the specification.
diff --git a/data/api/client-server/definitions/cross_signing_key.yaml b/data/api/client-server/definitions/cross_signing_key.yaml
index cebc5ecd..d937daab 100644
--- a/data/api/client-server/definitions/cross_signing_key.yaml
+++ b/data/api/client-server/definitions/cross_signing_key.yaml
@@ -35,6 +35,8 @@ properties:
       The public key.  The object must have exactly one property, whose name is
       in the form `<algorithm>:<unpadded_base64_public_key>`, and whose value
       is the unpadded base64 public key.
+    minProperties: 1
+    maxProperties: 1
     example:
       "ed25519:alice+base64+public+key": "alice+base64+public+key"
   signatures:
diff --git a/data/api/client-server/receipts.yaml b/data/api/client-server/receipts.yaml
index 27825001..0b8d4593 100644
--- a/data/api/client-server/receipts.yaml
+++ b/data/api/client-server/receipts.yaml
@@ -93,7 +93,8 @@ paths:
             application/json: {
               }
           schema:
-            type: object  # empty json object
+            type: object
+            maxProperties: 0  # empty json object
         429:
           description: This request was rate-limited.
           schema: