diff --git a/cmd/libs/go2idl/go-to-protobuf/protobuf/generator.go b/cmd/libs/go2idl/go-to-protobuf/protobuf/generator.go
index 5e3ed2efe40..ed826b9c3be 100644
--- a/cmd/libs/go2idl/go-to-protobuf/protobuf/generator.go
+++ b/cmd/libs/go2idl/go-to-protobuf/protobuf/generator.go
@@ -598,7 +598,7 @@ func protobufTagToField(tag string, field *protoField, m types.Member, t *types.
 			protoExtra[parts[0]] = parts[1]
 		case "casttype", "castkey", "castvalue":
 			parts[0] = fmt.Sprintf("(gogoproto.%s)", parts[0])
-			protoExtra[parts[0]] = parts[1]
+			protoExtra[parts[0]] = strconv.Quote(parts[1])
 		}
 	}