diff --git a/repmgr.c b/repmgr.c
index f6bf9963..8f3c8fe2 100644
--- a/repmgr.c
+++ b/repmgr.c
@@ -1903,7 +1903,7 @@ create_schema(PGconn *conn)
 	                  "  standby_node                   INTEGER NOT NULL, "
 	                  "  last_monitor_time              TIMESTAMP WITH TIME ZONE NOT NULL, "
 	                  "  last_wal_primary_location      TEXT NOT NULL,   "
-	                  "  last_wal_standby_location      TEXT NOT NULL,   "
+	                  "  last_wal_standby_location      TEXT,  "
 	                  "  replication_lag                BIGINT NOT NULL, "
 	                  "  apply_lag                      BIGINT NOT NULL) ", repmgr_schema);
 	log_debug(_("master register: %s\n"), sqlquery);
diff --git a/repmgr.sql b/repmgr.sql
index a2a6d43e..204bb45d 100644
--- a/repmgr.sql
+++ b/repmgr.sql
@@ -28,7 +28,7 @@ CREATE TABLE repl_monitor (
   standby_node                   INTEGER NOT NULL,
   last_monitor_time                      TIMESTAMP WITH TIME ZONE NOT NULL,
   last_wal_primary_location      TEXT NOT NULL,
-  last_wal_standby_location      TEXT NOT NULL,
+  last_wal_standby_location      TEXT,		-- In case of a witness server this will be NULL
   replication_lag                BIGINT NOT NULL,
   apply_lag                      BIGINT NOT NULL
 );