diff --git a/grpc.proto b/grpc.proto
index ddc9451..2d3073b 100644
--- a/grpc.proto
+++ b/grpc.proto
@@ -2,6 +2,7 @@ syntax = "proto3";
 package eu.ostrzyciel.jelly.core.proto.v1;
 
 // gRPC service specifications for RDF streaming.
+// Protocol version: 1.0.0
 
 import "rdf.proto";
 
diff --git a/rdf.proto b/rdf.proto
index 0f7e2d2..776f9dd 100644
--- a/rdf.proto
+++ b/rdf.proto
@@ -2,6 +2,7 @@ syntax = "proto3";
 package eu.ostrzyciel.jelly.core.proto.v1;
 
 // Jelly RDF serialization with Protocol Buffers.
+// Protocol version: 1.0.0
 
 // RDF IRIs
 // Either prefix_id or name_id can be zero if the prefix or the suffix are not used.