diff --git a/src/event/ServerSocket.hxx b/src/event/ServerSocket.hxx
index 7c69225b3..6ad1ab8a3 100644
--- a/src/event/ServerSocket.hxx
+++ b/src/event/ServerSocket.hxx
@@ -109,6 +109,10 @@ public:
 	 */
 	void AddFD(int fd);
 
+	bool IsEmpty() const noexcept {
+		return sockets.empty();
+	}
+
 	/**
 	 * Throws #std::runtime_error on error.
 	 */