diff --git a/go.mod b/go.mod
index 269f7ab..4872926 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,6 @@
 go 1.9
 
 require (
-	github.com/google/go-cmp v0.3.1
-	google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd
+	github.com/google/go-cmp v0.4.0
+	google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64
 )
diff --git a/go.sum b/go.sum
index 6cbf9e7..e5a2e4e 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,10 @@
+github.com/golang/protobuf v1.4.0-rc.1/go.mod h1:ceaxUfeHdC40wWswd/P6IGgMaK3YpKi5j83Wpe3EHw8=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
-github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
-google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd h1:zSMqFwpTkfj+1nNFgmgu4B+Qv5Kpf4jpd11lCmHKuwQ=
+github.com/google/go-cmp v0.4.0 h1:xsAVV57WRhGj6kEIi8ReJzQlHHqcBYCElAvkovg3B/4=
+github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
+google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64 h1:BhpvsYSxWvxATQJYrD9UKX1U3jo+Bxq195IzJGtyh40=
+google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
diff --git a/proto/wire.go b/proto/wire.go
index 53196ab..5e8b7ac 100644
--- a/proto/wire.go
+++ b/proto/wire.go
@@ -6,6 +6,7 @@
 
 import (
 	protoV2 "google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/runtime/protoiface"
 	"google.golang.org/protobuf/runtime/protoimpl"
 )
 
@@ -61,12 +62,17 @@
 // UnmarshalMerge parses a wire-format message in b and places the decoded results in m.
 func UnmarshalMerge(b []byte, m Message) error {
 	mi := protoimpl.X.ProtoMessageV2Of(m)
-	err := protoV2.UnmarshalOptions{
+	out, err := protoV2.UnmarshalOptions{
 		AllowPartial: true,
 		Merge:        true,
-	}.Unmarshal(b, mi)
+	}.UnmarshalState(mi, protoiface.UnmarshalInput{
+		Buf: b,
+	})
 	if err != nil {
 		return err
 	}
+	if out.Flags&protoiface.UnmarshalInitialized > 0 {
+		return nil
+	}
 	return checkRequiredNotSet(mi)
 }
diff --git a/protoc-gen-go/descriptor/descriptor.pb.go b/protoc-gen-go/descriptor/descriptor.pb.go
index a6d156a..63dc057 100644
--- a/protoc-gen-go/descriptor/descriptor.pb.go
+++ b/protoc-gen-go/descriptor/descriptor.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	descriptorpb "google.golang.org/protobuf/types/descriptorpb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/descriptor.proto.
@@ -167,18 +166,6 @@
 	0x6f, 0x74, 0x6f, 0x32,
 }
 
-var (
-	file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescData = file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/protoc-gen-go/plugin/plugin.pb.go b/protoc-gen-go/plugin/plugin.pb.go
index df86663..2704536 100644
--- a/protoc-gen-go/plugin/plugin.pb.go
+++ b/protoc-gen-go/plugin/plugin.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	pluginpb "google.golang.org/protobuf/types/pluginpb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/compiler/plugin.proto.
@@ -34,18 +33,6 @@
 	0x67, 0x6f, 0x50, 0x00, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x32,
 }
 
-var (
-	file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescData = file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/any/any.pb.go b/ptypes/any/any.pb.go
index a12e7d5..0ef27d3 100644
--- a/ptypes/any/any.pb.go
+++ b/ptypes/any/any.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	anypb "google.golang.org/protobuf/types/known/anypb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/any.proto.
@@ -29,18 +28,6 @@
 	0x74, 0x6f, 0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescData = file_github_com_golang_protobuf_ptypes_any_any_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_any_any_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_any_any_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_any_any_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/duration/duration.pb.go b/ptypes/duration/duration.pb.go
index 6bb3b2a..d0079ee 100644
--- a/ptypes/duration/duration.pb.go
+++ b/ptypes/duration/duration.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	durationpb "google.golang.org/protobuf/types/known/durationpb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/duration.proto.
@@ -30,18 +29,6 @@
 	0x6f, 0x6e, 0x50, 0x00, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescData = file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_duration_duration_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_duration_duration_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/empty/empty.pb.go b/ptypes/empty/empty.pb.go
index 5cab9ad..16686a6 100644
--- a/ptypes/empty/empty.pb.go
+++ b/ptypes/empty/empty.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	emptypb "google.golang.org/protobuf/types/known/emptypb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/empty.proto.
@@ -29,18 +28,6 @@
 	0x70, 0x74, 0x79, 0x50, 0x00, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescData = file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_empty_empty_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_empty_empty_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/struct/struct.pb.go b/ptypes/struct/struct.pb.go
index 66298b5..8d82abe 100644
--- a/ptypes/struct/struct.pb.go
+++ b/ptypes/struct/struct.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	structpb "google.golang.org/protobuf/types/known/structpb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/struct.proto.
@@ -45,18 +44,6 @@
 	0x6f, 0x74, 0x6f, 0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescData = file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_struct_struct_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_struct_struct_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/timestamp/timestamp.pb.go b/ptypes/timestamp/timestamp.pb.go
index 5c10e7e..a76f807 100644
--- a/ptypes/timestamp/timestamp.pb.go
+++ b/ptypes/timestamp/timestamp.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/timestamp.proto.
@@ -31,18 +30,6 @@
 	0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescData = file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type
diff --git a/ptypes/wrappers/wrappers.pb.go b/ptypes/wrappers/wrappers.pb.go
index c0cbd2f..cc40f27 100644
--- a/ptypes/wrappers/wrappers.pb.go
+++ b/ptypes/wrappers/wrappers.pb.go
@@ -8,7 +8,6 @@
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	wrapperspb "google.golang.org/protobuf/types/known/wrapperspb"
 	reflect "reflect"
-	sync "sync"
 )
 
 // Symbols defined in public import of google/protobuf/wrappers.proto.
@@ -38,18 +37,6 @@
 	0x72, 0x73, 0x50, 0x00, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
-var (
-	file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescOnce sync.Once
-	file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescData = file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDesc
-)
-
-func file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescGZIP() []byte {
-	file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescOnce.Do(func() {
-		file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescData = protoimpl.X.CompressGZIP(file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescData)
-	})
-	return file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDescData
-}
-
 var file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_goTypes = []interface{}{}
 var file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_depIdxs = []int32{
 	0, // [0:0] is the sub-list for method output_type