diff --git a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
index 4ab8623824e..f9b8af9b78d 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
@@ -7318,7 +7318,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
 	}
 
 	now = mstate.dtms_timestamp = dtrace_gethrtime();
-	mstate.dtms_present |= DTRACE_MSTATE_TIMESTAMP;
+	mstate.dtms_present = DTRACE_MSTATE_TIMESTAMP;
 	vtime = dtrace_vtime_references != 0;
 
 	if (vtime && curthread->t_dtrace_start)