diff --git a/usr.bin/truss/syscall.h b/usr.bin/truss/syscall.h
index 74fbcb7b254..c7094230370 100644
--- a/usr.bin/truss/syscall.h
+++ b/usr.bin/truss/syscall.h
@@ -122,6 +122,7 @@ enum Argtype {
 	Rtpriofunc,
 	RusageWho,
 	Schedpolicy,
+	ShmFlags,
 	Shutdown,
 	Signal,
 	Sigprocmask,
diff --git a/usr.bin/truss/syscalls.c b/usr.bin/truss/syscalls.c
index 721fbd23f8d..31192b37a52 100644
--- a/usr.bin/truss/syscalls.c
+++ b/usr.bin/truss/syscalls.c
@@ -471,6 +471,9 @@ static struct syscall decoded_syscalls[] = {
 		    { Ptr | IN, 3 }, { Socklent, 4 } } },
 	{ .name = "shm_open", .ret_type = 1, .nargs = 3,
 	  .args = { { ShmName | IN, 0 }, { Open, 1 }, { Octal, 2 } } },
+	{ .name = "shm_open2", .ret_type = 1, .nargs = 5,
+	  .args = { { ShmName | IN, 0 }, { Open, 1 }, { Octal, 2 },
+		    { ShmFlags, 3 }, { BinString | IN, 4 } } },
 	{ .name = "shm_rename", .ret_type = 1, .nargs = 3,
 	  .args = { { Name | IN, 0 }, { Name | IN, 1 }, { Hex, 2 } } },
 	{ .name = "shm_unlink", .ret_type = 1, .nargs = 1,
@@ -2009,6 +2012,9 @@ print_arg(struct syscall_args *sc, unsigned long *args, register_t *retval,
 	case Whence:
 		print_integer_arg(sysdecode_whence, fp, args[sc->offset]);
 		break;
+	case ShmFlags:
+		print_mask_arg(sysdecode_shmflags, fp, args[sc->offset]);
+		break;
 	case Sockdomain:
 		print_integer_arg(sysdecode_socketdomain, fp, args[sc->offset]);
 		break;