Build fails

[manfredlotz]

running make I get:

protoc -I rpc rpc/rpc.proto --go_out=plugins=grpc:rpc
google/protobuf/empty.proto: File not found.
google/protobuf/timestamp.proto: File not found.
rpc.proto: Import "google/protobuf/empty.proto" was not found or had errors.
rpc.proto: Import "google/protobuf/timestamp.proto" was not found or had errors.
rpc.proto:66:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:68:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:69:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:70:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:133:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:134:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:143:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:144:5: "google.protobuf.Timestamp" is not defined.
rpc.proto:7:21: "google.protobuf.Empty" is not defined.
rpc.proto:8:18: "google.protobuf.Empty" is not defined.
rpc.proto:8:50: "google.protobuf.Empty" is not defined.
rpc.proto:9:17: "google.protobuf.Empty" is not defined.
rpc.proto:9:49: "google.protobuf.Empty" is not defined.
rpc.proto:10:53: "google.protobuf.Empty" is not defined.
rpc.proto:11:15: "google.protobuf.Empty" is not defined.
rpc.proto:15:49: "google.protobuf.Empty" is not defined.
rpc.proto:16:63: "google.protobuf.Empty" is not defined.
rpc.proto:20:15: "google.protobuf.Empty" is not defined.
rpc.proto:20:47: "google.protobuf.Empty" is not defined.
make: *** [Makefile:36: rpc/rpc.pb.go] Error 1

This is a Fedora 31 where libprotoc is v3.6.1. FWIW, go is go version go1.13.3 linux/amd64