diff --git a/kern/include/test.h b/kern/include/test.h
index 9445a5c..68f0c73 100644
--- a/kern/include/test.h
+++ b/kern/include/test.h
@@ -61,6 +61,8 @@ int semtest(int, char **);
 int locktest(int, char **);
 int locktest2(int, char **);
 int locktest3(int, char **);
+int locktest4(int, char **);
+int locktest5(int, char **);
 int cvtest(int, char **);
 int cvtest2(int, char **);
 int cvtest3(int, char **);
@@ -156,7 +158,7 @@ void whalemating_cleanup(void);
 void male(uint32_t);
 void female(uint32_t);
 void matchmaker(uint32_t);
- 
+
 /*
  * stoplight.c.
  */
diff --git a/kern/main/menu.c b/kern/main/menu.c
index c104187..d9eaf2a 100644
--- a/kern/main/menu.c
+++ b/kern/main/menu.c
@@ -593,6 +593,8 @@ static const char *testmenu[] = {
 	"[lt1]  Lock test 1           (1)    ",
 	"[lt2]  Lock test 2           (1*)   ",
 	"[lt3]  Lock test 3           (1*)   ",
+	"[lt4]  Lock test 4           (1*)   ",
+	"[lt5]  Lock test 5           (1*)   ",
 	"[cvt1] CV test 1             (1)    ",
 	"[cvt2] CV test 2             (1)    ",
 	"[cvt3] CV test 3             (1*)   ",
@@ -743,6 +745,8 @@ static struct {
 	{ "lt1",	locktest },
 	{ "lt2",	locktest2 },
 	{ "lt3",	locktest3 },
+	{ "lt4", 	locktest4 },
+	{ "lt5", 	locktest5 },
 	{ "cvt1",	cvtest },
 	{ "cvt2",	cvtest2 },
 	{ "cvt3",	cvtest3 },
diff --git a/kern/test/synchtest.c b/kern/test/synchtest.c
index 23bb151..0639ddc 100644
--- a/kern/test/synchtest.c
+++ b/kern/test/synchtest.c
@@ -238,7 +238,6 @@ fail2:
 	return;
 }
 
-
 int
 locktest(int nargs, char **args)
 {
@@ -289,6 +288,13 @@ locktest(int nargs, char **args)
 	return 0;
 }
 
+/*
+ * Note that the following tests that panic on success do minimal cleanup
+ * afterward. This is to avoid causing a panic that could be unintentiontally
+ * considered a success signal by test161. As a result, they leak memory,
+ * don't destroy synchronization primitives, etc.
+ */
+
 int
 locktest2(int nargs, char **args) {
 	(void)nargs;
@@ -309,9 +315,9 @@ locktest2(int nargs, char **args) {
 
 	success(TEST161_FAIL, SECRET, "lt2");
 
-	lock_destroy(testlock);
-	testlock = NULL;
+	/* Don't do anything that could panic. */
 
+	testlock = NULL;
 	return 0;
 }
 
@@ -336,11 +342,110 @@ locktest3(int nargs, char **args) {
 
 	success(TEST161_FAIL, SECRET, "lt3");
 
-	testlock = NULL;
+	/* Don't do anything that could panic. */
 
+	testlock = NULL;
 	return 0;
 }
 
+/*
+ * Used by both lt4 and lt5 below. Simply acquires a lock in a separate
+ * thread. Uses a semaphore as a barrier to make sure it gets the lock before
+ * the driver completes.
+ */
+
+static
+void
+locktestacquirer(void * junk, unsigned long num)
+{
+  (void)junk;
+	(void)num;
+
+  lock_acquire(testlock);
+  V(donesem);
+
+	return;
+}
+
+
+int
+locktest4(int nargs, char **args) {
+  (void) nargs;
+  (void) args;
+
+  kprintf_n("Starting lt4...\n");
+  kprintf_n("(This test panics on success!)\n");
+
+  testlock = lock_create("testlock");
+  if (testlock == NULL) {
+	 panic("lt4: lock_create failed\n");
+  }
+
+  donesem = sem_create("donesem", 0);
+  if (donesem == NULL) {
+	 lock_destroy(testlock);
+	 panic("lt4: sem_create failed\n");
+  }
+
+	result = thread_fork("lt4", NULL, locktestacquirer, NULL, 0);
+	if (result) {
+		panic("lt4: thread_fork failed: %s\n", strerror(result));
+	}
+
+	P(donesem);
+	secprintf(SECRET, "Should panic...", "lt4");
+	lock_release(testlock);
+
+  /* Should not get here on success. */
+
+  success(TEST161_FAIL, SECRET, "lt4");
+
+	/* Don't do anything that could panic. */
+
+	testlock = NULL;
+  donesem = NULL;
+  return 0;
+}
+
+int
+locktest5(int nargs, char **args) {
+  (void) nargs;
+  (void) args;
+
+  kprintf_n("Starting lt5...\n");
+  kprintf_n("(This test panics on success!)\n");
+
+  testlock = lock_create("testlock");
+  if (testlock == NULL) {
+	 panic("lt5: lock_create failed\n");
+  }
+
+  donesem = sem_create("donesem", 0);
+  if (donesem == NULL) {
+	 lock_destroy(testlock);
+	 panic("lt5: sem_create failed\n");
+  }
+
+	result = thread_fork("lt5", NULL, locktestacquirer, NULL, 0);
+	if (result) {
+		panic("lt5: thread_fork failed: %s\n", strerror(result));
+	}
+
+	P(donesem);
+	secprintf(SECRET, "Should panic...", "lt5");
+	KASSERT(!(lock_do_i_hold(testlock)));
+
+  /* Should not get here on success. */
+
+  success(TEST161_FAIL, SECRET, "lt5");
+
+	/* Don't do anything that could panic. */
+
+	testlock = NULL;
+  donesem = NULL;
+  return 0;
+}
+
 static
 void
 cvtestthread(void *junk, unsigned long num)