diff --git a/protobuf-codegen/src/gen/field/mod.rs b/protobuf-codegen/src/gen/field/mod.rs
index d6a5e44a4..0c1d66ad8 100644
--- a/protobuf-codegen/src/gen/field/mod.rs
+++ b/protobuf-codegen/src/gen/field/mod.rs
@@ -188,7 +188,16 @@ impl<'a> FieldGen<'a> {
 
                 FieldKind::Repeated(RepeatedField {
                     elem,
-                    packed: field.field.proto().options.get_or_default().packed(),
+                    packed: field
+                        .field
+                        .proto()
+                        .options
+                        .get_or_default()
+                        .packed
+                        .unwrap_or(match field.message.scope.file_scope.syntax() {
+                            Syntax::Proto2 => false,
+                            Syntax::Proto3 => true,
+                        }),
                 })
             }
             RuntimeFieldType::Singular(..) => {