diff --git a/layouts/partials/openapi/render-object-table.html b/layouts/partials/openapi/render-object-table.html
index 21a185e3..85597e14 100644
--- a/layouts/partials/openapi/render-object-table.html
+++ b/layouts/partials/openapi/render-object-table.html
@@ -107,26 +107,27 @@
 
     {{ end }}
 
- {{/* additionalProperties should either be an OpenAPI schema object, or a
-       boolean. If it's the former, look for a `description` and render it as a note.
-       If it's `true`, do nothing. If it's `false`, raise a build-time error:
-       "Everything is extensible in Matrix unless otherwise noted". */}}
-   {{ if (ne $additionalProperties nil )}}
+ {{/* If additionalProperties is true, do nothing.
+      If additionalProperties is nil, treat is as the default (true) and do nothing.
+      If additionalProperties is false, raise a build-time error:
+      "Everything is extensible in Matrix unless otherwise noted".
+      Otherwise, it should be an OpenAPI schema object. Include the description
+      of that schema object, if it exists. */}}
+ {{ if (and (ne $additionalProperties nil) (ne $additionalProperties true)) }}
+  {{ if (and (reflect.IsMap $additionalProperties)) -}}
+   {{ if (index $additionalProperties "description") -}}
   <tr class="row-additional-properties">
    <td colspan="3">
-        {{ if (and (reflect.IsMap $additionalProperties)) -}}
-            {{ if (index $additionalProperties "description") -}}
-<em>Notes on additional properties:</em> {{ $additionalProperties.description }}
-            {{ end }}
-            {{/* TODO: should we handle the case where additional properties are
-                       permitted, but must follow an explicit schema? */}}
-        {{ else if (not $additionalProperties) -}}
-             {{ errorf "Unexpected additionalProperties=false for %s" $title }}
-May **not** have additional properties.
-        {{ end }}
+    <em>Notes on additional properties:</em> {{ $additionalProperties.description }}
    </td>
   </tr>
-    {{ end }}
+   {{ end }}
+  {{/* TODO: should we handle the case where additional properties are
+             permitted, but must follow an explicit schema? */}}
+  {{ else if (not $additionalProperties) -}}
+   {{ errorf "Unexpected additionalProperties=false for %s" $title }}
+  {{ end }}
+ {{ end }}
 </table>
 
 {{ end }}