diff --git a/test/rt/nanos6/spawn-task-external-bad.c b/test/rt/nanos6/spawn-task-external-bad.c
index 5e0dbaf..044d340 100644
--- a/test/rt/nanos6/spawn-task-external-bad.c
+++ b/test/rt/nanos6/spawn-task-external-bad.c
@@ -15,6 +15,9 @@
 #include <time.h>
 
 #include "common.h"
+#include "compat.h"
+
+volatile int complete = 0;
 
 static double
 get_time_ms(void)
@@ -42,11 +45,19 @@ polling_func(void *arg)
 	}
 }
 
+static void
+complete_func(void *arg)
+{
+	UNUSED(arg);
+	complete = 1;
+}
+
 /* Call the nanos6_spawn_function from an external thread */
 static void *
 spawn(void *arg)
 {
-	nanos6_spawn_function(polling_func, arg, NULL, NULL, "polling_task");
+	nanos6_spawn_function(polling_func, arg,
+			complete_func, NULL, "polling_task");
 	return NULL;
 }
 
@@ -71,5 +82,10 @@ main(void)
 
 	#pragma oss taskwait
 
+	while (!complete)
+		sleep_us(100);
+
+	free(T);
+
 	return 0;
 }
diff --git a/test/rt/nanos6/spawn-task-external.c b/test/rt/nanos6/spawn-task-external.c
index 470c82c..5710148 100644
--- a/test/rt/nanos6/spawn-task-external.c
+++ b/test/rt/nanos6/spawn-task-external.c
@@ -18,6 +18,8 @@
 #include "compat.h"
 #include "ovni.h"
 
+volatile int complete = 0;
+
 static double
 get_time_ms(void)
 {
@@ -44,6 +46,13 @@ polling_func(void *arg)
 	}
 }
 
+static void
+complete_func(void *arg)
+{
+	UNUSED(arg);
+	complete = 1;
+}
+
 static inline void
 instr_thread_start(int32_t cpu, int32_t creator_tid, uint64_t tag)
 {
@@ -82,7 +91,8 @@ spawn(void *arg)
 	/* Inform ovni of this external thread */
 	instr_thread_start(-1, -1, 0);
 
-	nanos6_spawn_function(polling_func, arg, NULL, NULL, "polling_task");
+	nanos6_spawn_function(polling_func, arg,
+			complete_func, NULL, "polling_task");
 
 	/* Then inform that the thread finishes */
 	instr_thread_end();
@@ -111,5 +121,10 @@ main(void)
 
 	#pragma oss taskwait
 
+	while (!complete)
+		sleep_us(100);
+
+	free(T);
+
 	return 0;
 }
diff --git a/test/rt/nanos6/spawn-task.c b/test/rt/nanos6/spawn-task.c
index 61436bd..8ca2779 100644
--- a/test/rt/nanos6/spawn-task.c
+++ b/test/rt/nanos6/spawn-task.c
@@ -12,6 +12,9 @@
 #include <time.h>
 
 #include "common.h"
+#include "compat.h"
+
+volatile int complete = 0;
 
 static double
 get_time_ms(void)
@@ -39,6 +42,13 @@ polling_func(void *arg)
 	}
 }
 
+static void
+complete_func(void *arg)
+{
+	UNUSED(arg);
+	complete = 1;
+}
+
 int
 main(void)
 {
@@ -48,12 +58,18 @@ main(void)
 
 	*T = 100.0;
 
-	nanos6_spawn_function(polling_func, T, NULL, NULL, "polling_task");
+	nanos6_spawn_function(polling_func, T,
+			complete_func, NULL, "polling_task");
 
 	#pragma oss task label("dummy_task")
 	dummy_work(*T);
 
 	#pragma oss taskwait
 
+	while (!complete)
+		sleep_us(100);
+
+	free(T);
+
 	return 0;
 }