diff --git a/internal/impl/codec_message.go b/internal/impl/codec_message.go
index 2f7b363..111d958 100644
--- a/internal/impl/codec_message.go
+++ b/internal/impl/codec_message.go
@@ -118,12 +118,12 @@
 				},
 			}
 		case isOneof:
-			fieldOffset = offsetOf(fs, mi.Exporter)
+			fieldOffset = offsetOf(fs)
 		case fd.IsWeak():
 			fieldOffset = si.weakOffset
 			funcs = makeWeakMessageFieldCoder(fd)
 		default:
-			fieldOffset = offsetOf(fs, mi.Exporter)
+			fieldOffset = offsetOf(fs)
 			childMessage, funcs = fieldCoder(fd, ft)
 		}
 		cf := &preallocFields[i]
diff --git a/internal/impl/codec_message_opaque.go b/internal/impl/codec_message_opaque.go
index 88c16ae..f81d7d0 100644
--- a/internal/impl/codec_message_opaque.go
+++ b/internal/impl/codec_message_opaque.go
@@ -45,19 +45,19 @@
 		var childMessage *MessageInfo
 		switch {
 		case fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic():
-			fieldOffset = offsetOf(fs, mi.Exporter)
+			fieldOffset = offsetOf(fs)
 		case fd.IsWeak():
 			fieldOffset = si.weakOffset
 			funcs = makeWeakMessageFieldCoder(fd)
 		case fd.Message() != nil && !fd.IsMap():
-			fieldOffset = offsetOf(fs, mi.Exporter)
+			fieldOffset = offsetOf(fs)
 			if fd.IsList() {
 				childMessage, funcs = makeOpaqueRepeatedMessageFieldCoder(fd, ft)
 			} else {
 				childMessage, funcs = makeOpaqueMessageFieldCoder(fd, ft)
 			}
 		default:
-			fieldOffset = offsetOf(fs, mi.Exporter)
+			fieldOffset = offsetOf(fs)
 			childMessage, funcs = fieldCoder(fd, ft)
 		}
 		cf := &coderFieldInfo{
diff --git a/internal/impl/message.go b/internal/impl/message.go
index fa10a0f..d1f79b4 100644
--- a/internal/impl/message.go
+++ b/internal/impl/message.go
@@ -165,28 +165,28 @@
 		switch f := t.Field(i); f.Name {
 		case genid.SizeCache_goname, genid.SizeCacheA_goname:
 			if f.Type == sizecacheType {
-				si.sizecacheOffset = offsetOf(f, mi.Exporter)
+				si.sizecacheOffset = offsetOf(f)
 				si.sizecacheType = f.Type
 			}
 		case genid.WeakFields_goname, genid.WeakFieldsA_goname:
 			if f.Type == weakFieldsType {
-				si.weakOffset = offsetOf(f, mi.Exporter)
+				si.weakOffset = offsetOf(f)
 				si.weakType = f.Type
 			}
 		case genid.UnknownFields_goname, genid.UnknownFieldsA_goname:
 			if f.Type == unknownFieldsAType || f.Type == unknownFieldsBType {
-				si.unknownOffset = offsetOf(f, mi.Exporter)
+				si.unknownOffset = offsetOf(f)
 				si.unknownType = f.Type
 			}
 		case genid.ExtensionFields_goname, genid.ExtensionFieldsA_goname, genid.ExtensionFieldsB_goname:
 			if f.Type == extensionFieldsType {
-				si.extensionOffset = offsetOf(f, mi.Exporter)
+				si.extensionOffset = offsetOf(f)
 				si.extensionType = f.Type
 			}
 		case "lazyFields", "XXX_lazyUnmarshalInfo":
-			si.lazyOffset = offsetOf(f, mi.Exporter)
+			si.lazyOffset = offsetOf(f)
 		case "XXX_presence":
-			si.presenceOffset = offsetOf(f, mi.Exporter)
+			si.presenceOffset = offsetOf(f)
 		default:
 			for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
 				if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
diff --git a/internal/impl/message_opaque.go b/internal/impl/message_opaque.go
index d7ec53f..d8dcd78 100644
--- a/internal/impl/message_opaque.go
+++ b/internal/impl/message_opaque.go
@@ -142,7 +142,7 @@
 	if ft.Kind() != reflect.Map {
 		panic(fmt.Sprintf("invalid type: got %v, want map kind", ft))
 	}
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	conv := NewConverter(ft, fd)
 	return fieldInfo{
 		fieldDesc: fd,
@@ -196,7 +196,7 @@
 		panic(fmt.Sprintf("invalid type: got %v, want slice kind", ft))
 	}
 	conv := NewConverter(reflect.PtrTo(ft), fd)
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	index, _ := presenceIndex(mi.Desc, fd)
 	return fieldInfo{
 		fieldDesc: fd,
@@ -246,7 +246,7 @@
 		panic(fmt.Sprintf("invalid type: got %v, want slice kind", ft))
 	}
 	conv := NewConverter(ft, fd)
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	index, _ := presenceIndex(mi.Desc, fd)
 	fieldNumber := fd.Number()
 	return fieldInfo{
@@ -339,7 +339,7 @@
 		panic(fmt.Sprintf("invalid type: got %v, want slice kind", ft))
 	}
 	conv := NewConverter(ft, fd)
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	return fieldInfo{
 		fieldDesc: fd,
 		has: func(p pointer) bool {
@@ -411,7 +411,7 @@
 		deref = true
 	}
 	conv := NewConverter(ft, fd)
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	index, _ := presenceIndex(mi.Desc, fd)
 	var getter func(p pointer) protoreflect.Value
 	if !nullable {
@@ -480,7 +480,7 @@
 func (mi *MessageInfo) fieldInfoForMessageOpaque(si opaqueStructInfo, fd protoreflect.FieldDescriptor, fs reflect.StructField) fieldInfo {
 	ft := fs.Type
 	conv := NewConverter(ft, fd)
-	fieldOffset := offsetOf(fs, mi.Exporter)
+	fieldOffset := offsetOf(fs)
 	index, _ := presenceIndex(mi.Desc, fd)
 	fieldNumber := fd.Number()
 	elemType := fs.Type.Elem()
diff --git a/internal/impl/message_reflect_field.go b/internal/impl/message_reflect_field.go
index 75e2def..9efecd4 100644
--- a/internal/impl/message_reflect_field.go
+++ b/internal/impl/message_reflect_field.go
@@ -76,7 +76,7 @@
 	isMessage := fd.Message() != nil
 
 	// TODO: Implement unsafe fast path?
-	fieldOffset := offsetOf(fs, x)
+	fieldOffset := offsetOf(fs)
 	return fieldInfo{
 		// NOTE: The logic below intentionally assumes that oneof fields are
 		// well-formatted. That is, the oneof interface never contains a
@@ -152,7 +152,7 @@
 	conv := NewConverter(ft, fd)
 
 	// TODO: Implement unsafe fast path?
-	fieldOffset := offsetOf(fs, x)
+	fieldOffset := offsetOf(fs)
 	return fieldInfo{
 		fieldDesc: fd,
 		has: func(p pointer) bool {
@@ -205,7 +205,7 @@
 	conv := NewConverter(reflect.PtrTo(ft), fd)
 
 	// TODO: Implement unsafe fast path?
-	fieldOffset := offsetOf(fs, x)
+	fieldOffset := offsetOf(fs)
 	return fieldInfo{
 		fieldDesc: fd,
 		has: func(p pointer) bool {
@@ -269,7 +269,7 @@
 		}
 	}
 	conv := NewConverter(ft, fd)
-	fieldOffset := offsetOf(fs, x)
+	fieldOffset := offsetOf(fs)
 
 	// Generate specialized getter functions to avoid going through reflect.Value
 	if nullable {
@@ -410,7 +410,7 @@
 	conv := NewConverter(ft, fd)
 
 	// TODO: Implement unsafe fast path?
-	fieldOffset := offsetOf(fs, x)
+	fieldOffset := offsetOf(fs)
 	return fieldInfo{
 		fieldDesc: fd,
 		has: func(p pointer) bool {
@@ -466,7 +466,7 @@
 	oi := &oneofInfo{oneofDesc: od}
 	if od.IsSynthetic() {
 		fs := si.fieldsByNumber[od.Fields().Get(0).Number()]
-		fieldOffset := offsetOf(fs, x)
+		fieldOffset := offsetOf(fs)
 		oi.which = func(p pointer) protoreflect.FieldNumber {
 			if p.IsNil() {
 				return 0
@@ -479,7 +479,7 @@
 		}
 	} else {
 		fs := si.oneofsByName[od.Name()]
-		fieldOffset := offsetOf(fs, x)
+		fieldOffset := offsetOf(fs)
 		oi.which = func(p pointer) protoreflect.FieldNumber {
 			if p.IsNil() {
 				return 0
diff --git a/internal/impl/pointer_unsafe.go b/internal/impl/pointer_unsafe.go
index 041ebde..6bed45e 100644
--- a/internal/impl/pointer_unsafe.go
+++ b/internal/impl/pointer_unsafe.go
@@ -22,7 +22,7 @@
 type offset uintptr
 
 // offsetOf returns a field offset for the struct field.
-func offsetOf(f reflect.StructField, x exporter) offset {
+func offsetOf(f reflect.StructField) offset {
 	return offset(f.Offset)
 }