diff --git a/src/core/editor/pdf_editor.js b/src/core/editor/pdf_editor.js
index 2ed888c73..8c68f70bb 100644
--- a/src/core/editor/pdf_editor.js
+++ b/src/core/editor/pdf_editor.js
@@ -27,7 +27,15 @@ import {
   getNewAnnotationsMap,
   numberToString,
 } from "../core_utils.js";
-import { Dict, isName, Name, Ref, RefSet, RefSetCache } from "../primitives.js";
+import {
+  Dict,
+  isDict,
+  isName,
+  Name,
+  Ref,
+  RefSet,
+  RefSetCache,
+} from "../primitives.js";
 import { incrementalUpdate, writeValue } from "../writer.js";
 import { isArrayEqual, stringToBytes } from "../../shared/util.js";
 import { NameTree, NumberTree } from "../name_number_tree.js";
@@ -280,11 +288,7 @@ class PDFEditor {
       oldRefMapping.put(oldRef, newRef);
 
       if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
-        if (
-          obj instanceof Dict &&
-          isName(obj.get("Type"), "Page") &&
-          !this.currentDocument.pagesMap.has(oldRef)
-        ) {
+        if (isDict(obj, "Page") && !this.currentDocument.pagesMap.has(oldRef)) {
           throw new Error(
             "Add a deleted page to the document is not supported."
           );
diff --git a/src/core/struct_tree.js b/src/core/struct_tree.js
index af57f0a5d..4ecbcb661 100644
--- a/src/core/struct_tree.js
+++ b/src/core/struct_tree.js
@@ -19,7 +19,7 @@ import {
   stringToUTF8String,
   warn,
 } from "../shared/util.js";
-import { Dict, isName, Name, Ref, RefSetCache } from "./primitives.js";
+import { Dict, isDict, isName, Name, Ref, RefSetCache } from "./primitives.js";
 import { stringToAsciiOrUTF16BE, stringToPDFString } from "./string_utils.js";
 import { BaseStream } from "./base_stream.js";
 import { lookupNormalRect } from "./core_utils.js";
@@ -594,10 +594,7 @@ class StructElementNode {
     }
     for (let af of AFs) {
       af = this.xref.fetchIfRef(af);
-      if (!(af instanceof Dict)) {
-        continue;
-      }
-      if (!isName(af.get("Type"), "Filespec")) {
+      if (!isDict(af, "Filespec")) {
         continue;
       }
       if (!isName(af.get("AFRelationship"), "Supplement")) {