1 files changed, 7 insertions, 4 deletions
diff --git a/src/proto/inst.proto b/src/proto/inst.proto
index d561661f1..2a5dd9516 100644
--- a/src/proto/inst.proto
+++ b/src/proto/inst.proto
@@ -52,10 +52,13 @@ message InstHeader {
 
 message Inst {
   required uint64 pc = 1;
-  oneof inst_oneof {
-    fixed32 inst = 2;
-    bytes inst_bytes = 9;
-  }
+
+  // Either inst or inst_bytes must be used, but never both. That should be
+  // enforced by the oneof keyword, but that's not supported in all versions
+  // of protobuf syntax we need to work with for now.
+  optional fixed32 inst = 2;
+  optional bytes inst_bytes = 9;
+
   optional uint32 nodeid = 3;
   optional uint32 cpuid = 4;
   optional fixed64 tick = 5;