diff --git a/Documentation/dev-guide/apispec/swagger/rpc.swagger.json b/Documentation/dev-guide/apispec/swagger/rpc.swagger.json
index 9e3b2a520f6..b2e0a00b270 100644
--- a/Documentation/dev-guide/apispec/swagger/rpc.swagger.json
+++ b/Documentation/dev-guide/apispec/swagger/rpc.swagger.json
@@ -2982,7 +2982,7 @@
         },
         "canceled": {
           "type": "boolean",
-          "description": "canceled is set to true if the response is for a cancel watch request.\nNo further events will be sent to the canceled watcher."
+          "description": "canceled is set to true if the response is for a cancel watch request\nor if the start_revision has already been compacted.\nNo further events will be sent to the canceled watcher."
         },
         "compact_revision": {
           "type": "string",
diff --git a/api/etcdserverpb/rpc.pb.go b/api/etcdserverpb/rpc.pb.go
index 208271bd9eb..87aec5c015a 100644
--- a/api/etcdserverpb/rpc.pb.go
+++ b/api/etcdserverpb/rpc.pb.go
@@ -2199,7 +2199,8 @@ type WatchResponse struct {
 	// the created watcher from the same stream.
 	// All events sent to the created watcher will attach with the same watch_id.
 	Created bool `protobuf:"varint,3,opt,name=created,proto3" json:"created,omitempty"`
-	// canceled is set to true if the response is for a cancel watch request.
+	// canceled is set to true if the response is for a cancel watch request
+	// or if the start_revision has already been compacted.
 	// No further events will be sent to the canceled watcher.
 	Canceled bool `protobuf:"varint,4,opt,name=canceled,proto3" json:"canceled,omitempty"`
 	// compact_revision is set to the minimum index if a watcher tries to watch
diff --git a/api/etcdserverpb/rpc.proto b/api/etcdserverpb/rpc.proto
index 344d163ac62..a4ace71ce2b 100644
--- a/api/etcdserverpb/rpc.proto
+++ b/api/etcdserverpb/rpc.proto
@@ -836,7 +836,8 @@ message WatchResponse {
   // All events sent to the created watcher will attach with the same watch_id.
   bool created = 3;
 
-  // canceled is set to true if the response is for a cancel watch request.
+  // canceled is set to true if the response is for a cancel watch request
+  // or if the start_revision has already been compacted.
   // No further events will be sent to the canceled watcher.
   bool canceled = 4;