diff --git a/ruby/ext/google/protobuf_c/map.c b/ruby/ext/google/protobuf_c/map.c
index 4ed80568af..5487a57640 100644
--- a/ruby/ext/google/protobuf_c/map.c
+++ b/ruby/ext/google/protobuf_c/map.c
@@ -495,7 +495,7 @@ VALUE Map_length(VALUE _self) {
   return ULL2NUM(upb_strtable_count(&self->table));
 }
 
-static VALUE Map_new_this_type(VALUE _self) {
+VALUE Map_new_this_type(VALUE _self) {
   Map* self = ruby_to_Map(_self);
   VALUE new_map = Qnil;
   VALUE key_type = fieldtype_to_ruby(self->key_type);
diff --git a/ruby/ext/google/protobuf_c/message.c b/ruby/ext/google/protobuf_c/message.c
index 2ba7b2fe47..4dd68f4a20 100644
--- a/ruby/ext/google/protobuf_c/message.c
+++ b/ruby/ext/google/protobuf_c/message.c
@@ -70,8 +70,6 @@ VALUE Message_alloc(VALUE klass) {
   msg = (MessageHeader*)ALLOC_N(uint8_t,
                                 sizeof(MessageHeader) + desc->layout->size);
 
-  memset(Message_data(msg), 0, desc->layout->size);
-
   // We wrap first so that everything in the message object is GC-rooted in case
   // a collection happens during object creation in layout_init().
   ret = TypedData_Wrap_Struct(klass, &Message_type, msg);
diff --git a/ruby/ext/google/protobuf_c/protobuf.h b/ruby/ext/google/protobuf_c/protobuf.h
index 5176d59f0c..6314b78810 100644
--- a/ruby/ext/google/protobuf_c/protobuf.h
+++ b/ruby/ext/google/protobuf_c/protobuf.h
@@ -419,6 +419,7 @@ extern VALUE cRepeatedField;
 
 RepeatedField* ruby_to_RepeatedField(VALUE value);
 
+VALUE RepeatedField_new_this_type(VALUE _self);
 VALUE RepeatedField_each(VALUE _self);
 VALUE RepeatedField_index(int argc, VALUE* argv, VALUE _self);
 void* RepeatedField_index_native(VALUE _self, int index);
@@ -467,6 +468,7 @@ extern VALUE cMap;
 
 Map* ruby_to_Map(VALUE value);
 
+VALUE Map_new_this_type(VALUE _self);
 VALUE Map_each(VALUE _self);
 VALUE Map_keys(VALUE _self);
 VALUE Map_values(VALUE _self);
@@ -522,11 +524,13 @@ struct MessageLayout {
   uint32_t size;
   uint32_t value_offset;
   int value_count;
+  int repeated_count;
+  int map_count;
 };
 
 #define ONEOF_CASE_MASK 0x80000000
 
-MessageLayout* create_layout(Descriptor* desc);
+void create_layout(Descriptor* desc);
 void free_layout(MessageLayout* layout);
 bool field_contains_hasbit(MessageLayout* layout,
                  const upb_fielddef* field);
diff --git a/ruby/ext/google/protobuf_c/repeated_field.c b/ruby/ext/google/protobuf_c/repeated_field.c
index 2766087504..1c649280fe 100644
--- a/ruby/ext/google/protobuf_c/repeated_field.c
+++ b/ruby/ext/google/protobuf_c/repeated_field.c
@@ -323,7 +323,7 @@ VALUE RepeatedField_length(VALUE _self) {
   return INT2NUM(self->size);
 }
 
-static VALUE RepeatedField_new_this_type(VALUE _self) {
+VALUE RepeatedField_new_this_type(VALUE _self) {
   RepeatedField* self = ruby_to_RepeatedField(_self);
   VALUE new_rptfield = Qnil;
   VALUE element_type = fieldtype_to_ruby(self->field_type);
diff --git a/ruby/ext/google/protobuf_c/storage.c b/ruby/ext/google/protobuf_c/storage.c
index ad76e4f87a..6922cdc456 100644
--- a/ruby/ext/google/protobuf_c/storage.c
+++ b/ruby/ext/google/protobuf_c/storage.c
@@ -478,7 +478,7 @@ bool is_value_field(const upb_fielddef* f) {
          upb_fielddef_isstring(f);
 }
 
-MessageLayout* create_layout(Descriptor* desc) {
+void create_layout(Descriptor* desc) {
   const upb_msgdef *msgdef = desc->msgdef;
   MessageLayout* layout = ALLOC(MessageLayout);
   int nfields = upb_msgdef_numfields(msgdef);
@@ -517,14 +517,49 @@ MessageLayout* create_layout(Descriptor* desc) {
 
   off = align_up_to(off, sizeof(VALUE));
   layout->value_offset = off;
+  layout->repeated_count = 0;
+  layout->map_count = 0;
   layout->value_count = 0;
 
-  // Place all (non-oneof) VALUE fields first.
+  // Place all VALUE fields for repeated fields.
   for (upb_msg_field_begin(&it, msgdef);
        !upb_msg_field_done(&it);
        upb_msg_field_next(&it)) {
     const upb_fielddef* field = upb_msg_iter_field(&it);
-    if (upb_fielddef_containingoneof(field) || !is_value_field(field)) {
+    if (upb_fielddef_containingoneof(field) || !upb_fielddef_isseq(field) ||
+        upb_fielddef_ismap(field)) {
+      continue;
+    }
+
+    layout->fields[upb_fielddef_index(field)].offset = off;
+    off += sizeof(VALUE);
+    layout->repeated_count++;
+  }
+
+  // Place all VALUE fields for map fields.
+  for (upb_msg_field_begin(&it, msgdef);
+       !upb_msg_field_done(&it);
+       upb_msg_field_next(&it)) {
+    const upb_fielddef* field = upb_msg_iter_field(&it);
+    if (upb_fielddef_containingoneof(field) || !upb_fielddef_isseq(field) ||
+        !upb_fielddef_ismap(field)) {
+      continue;
+    }
+
+    layout->fields[upb_fielddef_index(field)].offset = off;
+    off += sizeof(VALUE);
+    layout->map_count++;
+  }
+
+  layout->value_count = layout->repeated_count + layout->map_count;
+
+  // Next place all other (non-oneof) VALUE fields.
+  for (upb_msg_field_begin(&it, msgdef);
+       !upb_msg_field_done(&it);
+       upb_msg_field_next(&it)) {
+    const upb_fielddef* field = upb_msg_iter_field(&it);
+    if (upb_fielddef_containingoneof(field) || !is_value_field(field) ||
+        upb_fielddef_isseq(field)) {
       continue;
     }
 
@@ -909,7 +944,19 @@ void layout_set(MessageLayout* layout,
 }
 
 void layout_init(MessageLayout* layout, void* storage) {
+  VALUE* value = (VALUE*)CHARPTR_AT(storage, layout->value_offset);
+  int i;
+
   memcpy(storage, layout->empty_template, layout->size);
+
+  for (i = 0; i < layout->repeated_count; i++, value++) {
+    *value = RepeatedField_new_this_type(*value);
+  }
+
+  for (i = 0; i < layout->map_count; i++, value++) {
+    *value = Map_new_this_type(*value);
+  }
+
   /*
   upb_msg_field_iter it;
   for (upb_msg_field_begin(&it, layout->msgdef);