diff --git a/src/core/catalog.js b/src/core/catalog.js
index 8f09309b9..00524c32e 100644
--- a/src/core/catalog.js
+++ b/src/core/catalog.js
@@ -720,12 +720,12 @@ class Catalog {
         }
       }
     } else if (obj instanceof Dict) {
-      obj.forEach(function (key, value) {
+      for (const [key, value] of obj) {
         const dest = fetchDest(value);
         if (dest) {
           dests[key] = dest;
         }
-      });
+      }
     }
     return shadow(this, "destinations", dests);
   }
diff --git a/src/core/document.js b/src/core/document.js
index 3c2599233..1744066d1 100644
--- a/src/core/document.js
+++ b/src/core/document.js
@@ -1282,13 +1282,8 @@ class PDFDocument {
       },
     };
 
-    const fonts = new Map();
-    fontRes.forEach((fontName, font) => {
-      fonts.set(fontName, font);
-    });
     const promises = [];
-
-    for (const [fontName, font] of fonts) {
+    for (const [fontName, font] of fontRes) {
       const descriptor = font.get("FontDescriptor");
       if (!(descriptor instanceof Dict)) {
         continue;
diff --git a/src/core/primitives.js b/src/core/primitives.js
index bf556b538..c48a34eb7 100644
--- a/src/core/primitives.js
+++ b/src/core/primitives.js
@@ -203,14 +203,14 @@ class Dict {
     return this._map.has(key);
   }
 
-  forEach(callback) {
+  *[Symbol.iterator]() {
     for (const [key, value] of this._map) {
-      callback(
+      yield [
         key,
         value instanceof Ref && this.xref
           ? this.xref.fetch(value, this.suppressEncryption)
-          : value
-      );
+          : value,
+      ];
     }
   }
 
diff --git a/src/core/struct_tree.js b/src/core/struct_tree.js
index 7f5c7b45e..fa27a14c0 100644
--- a/src/core/struct_tree.js
+++ b/src/core/struct_tree.js
@@ -62,12 +62,11 @@ class StructTreeRoot {
     if (!(roleMapDict instanceof Dict)) {
       return;
     }
-    roleMapDict.forEach((key, value) => {
-      if (!(value instanceof Name)) {
-        return;
+    for (const [key, value] of roleMapDict) {
+      if (value instanceof Name) {
+        this.roleMap.set(key, value.name);
       }
-      this.roleMap.set(key, value.name);
-    });
+    }
   }
 
   static async canCreateStructureTree({
diff --git a/src/core/worker.js b/src/core/worker.js
index cba6cb0ce..e285d6491 100644
--- a/src/core/worker.js
+++ b/src/core/worker.js
@@ -688,11 +688,11 @@ class WorkerMessageHandler {
           const infoObj = Object.create(null);
           const xrefInfo = xref.trailer.get("Info") || null;
           if (xrefInfo instanceof Dict) {
-            xrefInfo.forEach((key, value) => {
+            for (const [key, value] of xrefInfo) {
               if (typeof value === "string") {
                 infoObj[key] = stringToPDFString(value);
               }
-            });
+            }
           }
 
           newXrefInfo = {
diff --git a/test/unit/primitives_spec.js b/test/unit/primitives_spec.js
index caefdf025..00c491004 100644
--- a/test/unit/primitives_spec.js
+++ b/test/unit/primitives_spec.js
@@ -221,17 +221,12 @@ describe("primitives", function () {
       expect(values[2]).toEqual(testFontFile);
     });
 
-    it("should callback for each stored key", function () {
-      const callbackSpy = jasmine.createSpy("spy on callback in dictionary");
-
-      dictWithManyKeys.forEach(callbackSpy);
-
-      expect(callbackSpy).toHaveBeenCalled();
-      const callbackSpyCalls = callbackSpy.calls;
-      expect(callbackSpyCalls.argsFor(0)).toEqual(["FontFile", testFontFile]);
-      expect(callbackSpyCalls.argsFor(1)).toEqual(["FontFile2", testFontFile2]);
-      expect(callbackSpyCalls.argsFor(2)).toEqual(["FontFile3", testFontFile3]);
-      expect(callbackSpyCalls.count()).toEqual(3);
+    it("should iterate through each stored key", function () {
+      expect([...dictWithManyKeys]).toEqual([
+        ["FontFile", testFontFile],
+        ["FontFile2", testFontFile2],
+        ["FontFile3", testFontFile3],
+      ]);
     });
 
     it("should handle keys pointing to indirect objects, both sync and async", async function () {