diff --git a/tools/lib/api/fd/array.h b/tools/lib/api/fd/array.h
index e87fd800fa8d38f0400e352280a70761afd518ee..71287dddc05fbf7ba58772fc7833a1a6d1505f13 100644
--- a/tools/lib/api/fd/array.h
+++ b/tools/lib/api/fd/array.h
@@ -22,6 +22,7 @@ struct fdarray {
 	struct pollfd *entries;
 	union {
 		int    idx;
+		void   *ptr;
 	} *priv;
 };