diff --git a/usr.bin/truss/syscalls.c b/usr.bin/truss/syscalls.c
--- a/usr.bin/truss/syscalls.c
+++ b/usr.bin/truss/syscalls.c
@@ -428,6 +428,9 @@
 	{ .name = "pread", .ret_type = 1, .nargs = 4,
 	  .args = { { Int, 0 }, { BinString | OUT, 1 }, { Sizet, 2 },
 		    { QuadHex, 3 } } },
+	{ .name = "preadv", .ret_type = 1, .nargs = 4,
+	  .args = { { Int, 0 }, { Iovec | OUT, 1 }, { Int, 2 },
+		    { QuadHex, 3 } } },
 	{ .name = "procctl", .ret_type = 1, .nargs = 4,
 	  .args = { { Idtype, 0 }, { Quad, 1 }, { Procctl, 2 }, { Ptr, 3 } } },
 	{ .name = "ptrace", .ret_type = 1, .nargs = 4,
@@ -435,6 +438,9 @@
 	{ .name = "pwrite", .ret_type = 1, .nargs = 4,
 	  .args = { { Int, 0 }, { BinString | IN, 1 }, { Sizet, 2 },
 		    { QuadHex, 3 } } },
+	{ .name = "pwritev", .ret_type = 1, .nargs = 4,
+	  .args = { { Int, 0 }, { Iovec | IN, 1 }, { Int, 2 },
+		    { QuadHex, 3 } } },
 	{ .name = "quotactl", .ret_type = 1, .nargs = 4,
 	  .args = { { Name, 0 }, { Quotactlcmd, 1 }, { Int, 2 }, { Ptr, 3 } } },
 	{ .name = "read", .ret_type = 1, .nargs = 3,