diff --git a/proto/generate.proto b/proto/generate.proto
index 98b3d026..cc14cbf8 100644
--- a/proto/generate.proto
+++ b/proto/generate.proto
@@ -132,7 +132,7 @@ message PrefillResponse {
     /// Generation
     repeated Generation generations = 1;
     /// Next batch (cached)
-    Batch batch = 2;
+    optional Batch batch = 2;
 }
 
 message DecodeRequest {
@@ -144,5 +144,5 @@ message DecodeResponse {
     /// Decodes
     repeated Generation generations = 1;
     /// Next batch (cached)
-    Batch batch = 2;
+    optional Batch batch = 2;
 }
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