diff --git a/test/emu/common/instr.h b/test/emu/common/instr.h
index f5c0d52..0e58fc0 100644
--- a/test/emu/common/instr.h
+++ b/test/emu/common/instr.h
@@ -62,6 +62,8 @@ int64_t get_delta(void);
 	}
 
 INSTR_3ARG(instr_thread_execute, "OHx", int32_t, cpu, int32_t, creator_tid, uint64_t, tag)
+INSTR_0ARG(instr_thread_pause, "OHp")
+INSTR_0ARG(instr_thread_resume, "OHr")
 INSTR_1ARG(instr_thread_affinity_set, "OAs", int32_t, cpu)
 
 static inline void
diff --git a/test/emu/ovni/libovni-mark.c b/test/emu/ovni/libovni-mark.c
index 8c1387b..56af5a2 100644
--- a/test/emu/ovni/libovni-mark.c
+++ b/test/emu/ovni/libovni-mark.c
@@ -51,9 +51,16 @@ main(void)
 
 		int which = 1 + (rand() % 3);
 
+		/* Simulate a thread goes to sleep */
+		if (rank == 0 && i == 25)
+			instr_thread_pause();
+
 		ovni_mark_push(MARK_COLORS, which);
 		rand_sleep(500);
 		ovni_mark_pop(MARK_COLORS, which);
+
+		if (rank == 0 && i == 75)
+			instr_thread_resume();
 	}
 
 	ovni_mark_set(MARK_PROGRESS, 100);