diff --git a/src/main/java/org/extendj/ragdoc/JsonBuilder.java b/src/main/java/org/extendj/ragdoc/JsonBuilder.java
index 0b0ac40f29914cf71597d25caa819789a3e0c63f..3b56ce98287ed8e15c4b456d917e67900743329b 100644
--- a/src/main/java/org/extendj/ragdoc/JsonBuilder.java
+++ b/src/main/java/org/extendj/ragdoc/JsonBuilder.java
@@ -422,6 +422,10 @@ public class JsonBuilder {
       ClassDecl klass = (ClassDecl) type;
       while (klass.hasSuperclass()) {
         ClassDecl superclass = (ClassDecl) klass.superclass();
+        if (superclass.isObject() || superclass.isUnknown()) {
+          // Don't include the object/unknown types in the type hierarchy.
+          break;
+        }
         JsonArray methodArray = new JsonArray();
         JsonArray attributeArray = new JsonArray();
         // Set to keep track of which method names have already been listed for