diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
index 4a27c641ad8b..557e0615821a 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
@@ -1483,7 +1483,7 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
 	}
 	if (scn->scn_visited_this_txg) {
 		zfs_dbgmsg("freed %llu blocks in %llums from "
-		    "free_bpobj/bptree txg %llu; err=%u",
+		    "free_bpobj/bptree txg %llu; err=%d",
 		    (longlong_t)scn->scn_visited_this_txg,
 		    (longlong_t)
 		    NSEC2MSEC(gethrtime() - scn->scn_sync_start_time),