diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index f941ee2faf..9dc31cb64a 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -383,3 +383,8 @@
  * Enable tracing of syncscan operations (see also the trace_syncscan GUC var).
  */
 /* #define TRACE_SYNCSCAN */
+
+/*
+ * Enable Percona specific features, should always be defined in this fork
+ */
+#define PERCONA_FORK 1