diff --git a/src/command/StickerCommands.cxx b/src/command/StickerCommands.cxx
index 0061da15bb..ecafdd0bf1 100644
--- a/src/command/StickerCommands.cxx
+++ b/src/command/StickerCommands.cxx
@@ -524,7 +524,12 @@ handle_sticker(Client &client, Request args, Response &r)
 			args.pop_back();
 		}
 
-		bool has_op = args.size() > 4;
+		if (args.size() != 4 && args.size() != 6) {
+			r.Error(ACK_ERROR_ARG, "bad request");
+			return CommandResult::ERROR;
+		}
+
+		const bool has_op = args.size() == 6;
 		auto value = has_op ? args[5] : nullptr;
 		StickerOperator op = StickerOperator::EXISTS;
 		if (has_op) {