diff --git a/packages/protobuf-bench/README.md b/packages/protobuf-bench/README.md
index 810e195e6..1f08d5a46 100644
--- a/packages/protobuf-bench/README.md
+++ b/packages/protobuf-bench/README.md
@@ -10,5 +10,5 @@ server would usually do.
 
 | code generator      | bundle size             | minified               | compressed         |
 |---------------------|------------------------:|-----------------------:|-------------------:|
-| protobuf-es         | 96,959 b      | 41,479 b | 10,750 b |
+| protobuf-es         | 97,101 b      | 41,461 b | 10,746 b |
 | protobuf-javascript | 394,384 b  | 288,654 b | 45,122 b |
diff --git a/packages/protobuf/src/private/util-common.ts b/packages/protobuf/src/private/util-common.ts
index 1a86873db..57a64740a 100644
--- a/packages/protobuf/src/private/util-common.ts
+++ b/packages/protobuf/src/private/util-common.ts
@@ -38,6 +38,7 @@ export function makeUtilCommon(): Omit<Util, "newFieldList" | "initFields"> {
           t = target as AnyMessage,
           s = source as PartialMessage<AnyMessage>;
         if (s[localName] === undefined) {
+          // TODO if source is a Message instance, we should use isFieldSet() here to support future field presence
           continue;
         }
         switch (member.kind) {
@@ -105,7 +106,7 @@ export function makeUtilCommon(): Omit<Util, "newFieldList" | "initFields"> {
               t[localName] = (s[localName] as any[]).map((val) =>
                 val instanceof mt ? val : new mt(val),
               );
-            } else if (s[localName] !== undefined) {
+            } else {
               const val = s[localName];
               if (mt.fieldWrapper) {
                 if (
@@ -124,6 +125,7 @@ export function makeUtilCommon(): Omit<Util, "newFieldList" | "initFields"> {
         }
       }
     },
+    // TODO use isFieldSet() here to support future field presence
     equals<T extends Message<T>>(
       type: MessageType<T>,
       a: T | PlainMessage<T> | undefined | null,
@@ -202,6 +204,7 @@ export function makeUtilCommon(): Omit<Util, "newFieldList" | "initFields"> {
         }
       });
     },
+    // TODO use isFieldSet() here to support future field presence
     clone<T extends Message<T>>(message: T): T {
       const type = message.getType(),
         target = new type(),
diff --git a/packages/protobuf/src/proto2.ts b/packages/protobuf/src/proto2.ts
index b4daa7e0f..292be5102 100644
--- a/packages/protobuf/src/proto2.ts
+++ b/packages/protobuf/src/proto2.ts
@@ -29,7 +29,7 @@ export const proto2 = makeProtoRuntime(
       normalizeFieldInfos(source, false),
     );
   },
-  // TODO merge with proto3 and initExtensionField
+  // TODO merge with proto3 and initExtensionField, also see initPartial, equals, clone
   (target: Message): void => {
     for (const member of target.getType().fields.byMember()) {
       const name = member.localName,
diff --git a/packages/protobuf/src/proto3.ts b/packages/protobuf/src/proto3.ts
index b4a1035e9..31c4b05da 100644
--- a/packages/protobuf/src/proto3.ts
+++ b/packages/protobuf/src/proto3.ts
@@ -30,7 +30,7 @@ export const proto3 = makeProtoRuntime(
       normalizeFieldInfos(source, true),
     );
   },
-  // TODO merge with proto2 and initExtensionField
+  // TODO merge with proto2 and initExtensionField, also see initPartial, equals, clone
   (target: Message): void => {
     for (const member of target.getType().fields.byMember()) {
       if (member.opt) {