diff --git a/src/proto/grSim_Commands.proto b/src/proto/grSim_Commands.proto
index fa892675..a09fee08 100644
--- a/src/proto/grSim_Commands.proto
+++ b/src/proto/grSim_Commands.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 message grSim_Robot_Command {
 required uint32 id = 1;
 required float kickspeedx = 2;
diff --git a/src/proto/grSim_Packet.proto b/src/proto/grSim_Packet.proto
index 5bf696f5..2c4e7acd 100644
--- a/src/proto/grSim_Packet.proto
+++ b/src/proto/grSim_Packet.proto
@@ -1,6 +1,8 @@
+syntax = "proto2";
+
 import "grSim_Commands.proto";
 import "grSim_Replacement.proto";
 message grSim_Packet {
     optional grSim_Commands commands = 1;
     optional grSim_Replacement replacement = 2;
-}
\ No newline at end of file
+}
diff --git a/src/proto/grSim_Replacement.proto b/src/proto/grSim_Replacement.proto
index da1ea31a..0aedb305 100644
--- a/src/proto/grSim_Replacement.proto
+++ b/src/proto/grSim_Replacement.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 message grSim_RobotReplacement {
 required double x=1;
 required double y=2;
diff --git a/src/proto/messages_robocup_ssl_detection.proto b/src/proto/messages_robocup_ssl_detection.proto
index ff50f410..918748c1 100644
--- a/src/proto/messages_robocup_ssl_detection.proto
+++ b/src/proto/messages_robocup_ssl_detection.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 message SSL_DetectionBall {
   required float  confidence = 1;
   optional uint32 area       = 2;
diff --git a/src/proto/messages_robocup_ssl_geometry.proto b/src/proto/messages_robocup_ssl_geometry.proto
index d4431b8f..6a0b9912 100644
--- a/src/proto/messages_robocup_ssl_geometry.proto
+++ b/src/proto/messages_robocup_ssl_geometry.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 // A 2D float vector.
 message Vector2f {
   required float x = 1;
diff --git a/src/proto/messages_robocup_ssl_refbox_log.proto b/src/proto/messages_robocup_ssl_refbox_log.proto
index 9ae6cd73..8a437bce 100644
--- a/src/proto/messages_robocup_ssl_refbox_log.proto
+++ b/src/proto/messages_robocup_ssl_refbox_log.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 import "messages_robocup_ssl_detection.proto";
 
 message Log_Frame
diff --git a/src/proto/messages_robocup_ssl_wrapper.proto b/src/proto/messages_robocup_ssl_wrapper.proto
index 25b6d2de..7d104d87 100644
--- a/src/proto/messages_robocup_ssl_wrapper.proto
+++ b/src/proto/messages_robocup_ssl_wrapper.proto
@@ -1,3 +1,5 @@
+syntax = "proto2";
+
 import "messages_robocup_ssl_detection.proto";
 import "messages_robocup_ssl_geometry.proto";