diff --git a/benchmark/grpc_testing/test.pb.go b/benchmark/grpc_testing/test.pb.go
index d454e578..261ba1cc 100644
--- a/benchmark/grpc_testing/test.pb.go
+++ b/benchmark/grpc_testing/test.pb.go
@@ -539,9 +539,9 @@ func RegisterTestServiceServer(s *grpc.Server, srv TestServiceServer) {
 	s.RegisterService(&_TestService_serviceDesc, srv)
 }
 
-func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(Empty)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).EmptyCall(ctx, in)
@@ -551,9 +551,9 @@ func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []
 	return out, nil
 }
 
-func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(SimpleRequest)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).UnaryCall(ctx, in)
diff --git a/examples/route_guide/proto/route_guide.pb.go b/examples/route_guide/proto/route_guide.pb.go
index c3d14b2c..5851e023 100644
--- a/examples/route_guide/proto/route_guide.pb.go
+++ b/examples/route_guide/proto/route_guide.pb.go
@@ -310,9 +310,9 @@ func RegisterRouteGuideServer(s *grpc.Server, srv RouteGuideServer) {
 	s.RegisterService(&_RouteGuide_serviceDesc, srv)
 }
 
-func _RouteGuide_GetFeature_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _RouteGuide_GetFeature_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(Point)
-	if err := proto1.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(RouteGuideServer).GetFeature(ctx, in)
diff --git a/interop/grpc_testing/test.pb.go b/interop/grpc_testing/test.pb.go
index d454e578..261ba1cc 100755
--- a/interop/grpc_testing/test.pb.go
+++ b/interop/grpc_testing/test.pb.go
@@ -539,9 +539,9 @@ func RegisterTestServiceServer(s *grpc.Server, srv TestServiceServer) {
 	s.RegisterService(&_TestService_serviceDesc, srv)
 }
 
-func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(Empty)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).EmptyCall(ctx, in)
@@ -551,9 +551,9 @@ func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []
 	return out, nil
 }
 
-func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(SimpleRequest)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).UnaryCall(ctx, in)
diff --git a/server.go b/server.go
index 716ab6ad..79f17f3d 100644
--- a/server.go
+++ b/server.go
@@ -49,7 +49,7 @@ import (
 	"google.golang.org/grpc/transport"
 )
 
-type methodHandler func(srv interface{}, ctx context.Context, buf []byte) (interface{}, error)
+type methodHandler func(srv interface{}, ctx context.Context, codec Codec, buf []byte) (interface{}, error)
 
 // MethodDesc represents an RPC service's method specification.
 type MethodDesc struct {
@@ -253,7 +253,7 @@ func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.
 		case compressionNone:
 			statusCode := codes.OK
 			statusDesc := ""
-			reply, appErr := md.Handler(srv.server, stream.Context(), req)
+			reply, appErr := md.Handler(srv.server, stream.Context(), s.opts.codec, req)
 			if appErr != nil {
 				if err, ok := appErr.(rpcError); ok {
 					statusCode = err.code
diff --git a/test/grpc_testing/test.pb.go b/test/grpc_testing/test.pb.go
index d454e578..261ba1cc 100644
--- a/test/grpc_testing/test.pb.go
+++ b/test/grpc_testing/test.pb.go
@@ -539,9 +539,9 @@ func RegisterTestServiceServer(s *grpc.Server, srv TestServiceServer) {
 	s.RegisterService(&_TestService_serviceDesc, srv)
 }
 
-func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(Empty)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).EmptyCall(ctx, in)
@@ -551,9 +551,9 @@ func _TestService_EmptyCall_Handler(srv interface{}, ctx context.Context, buf []
 	return out, nil
 }
 
-func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, buf []byte) (interface{}, error) {
+func _TestService_UnaryCall_Handler(srv interface{}, ctx context.Context, codec grpc.Codec, buf []byte) (interface{}, error) {
 	in := new(SimpleRequest)
-	if err := proto.Unmarshal(buf, in); err != nil {
+	if err := codec.Unmarshal(buf, in); err != nil {
 		return nil, err
 	}
 	out, err := srv.(TestServiceServer).UnaryCall(ctx, in)