diff --git a/tests/pthread/tls.c b/tests/pthread/tls.c
index ab79f8b8c9..21a4a614c8 100644
--- a/tests/pthread/tls.c
+++ b/tests/pthread/tls.c
@@ -1,13 +1,12 @@
 #include <assert.h>
-// PTHREAD_KEYS_MAX
+// PTHREAD_KEYS_MAX, PTHREAD_DESTRUCTOR_ITERATIONS
 #include <limits.h>
 #include <pthread.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 
-pthread_key_t key_a;
-pthread_key_t key_b;
+pthread_key_t key_a, key_b, key_c, key_d, key_e;
 size_t total_destructor_runs = 0;
 
 void drop_key_a(void *val_a) {
@@ -48,16 +47,46 @@ void drop_key_b(void *val_b) {
     }
 }
 
+void drop_unreachable(void *val_c) {
+    // Should never be called.
+    (void)val_c;
+    assert(false);
+}
+
+void drop_key_d(void *val_d) {
+    assert(pthread_getspecific(key_d) == NULL && val_d == (void *)0xdddd);
+    // [`pthread_key_{create,setspecific,getspecific,delete}`] can still be used
+    // inside the destructor itself.
+    printf("drop_key_d(d=%p)\n", val_d);
+    pthread_key_t key_g;
+    assert(!pthread_key_create(&key_g, drop_unreachable));
+    assert(!pthread_setspecific(key_g, &key_g));
+    assert(pthread_getspecific(key_g) == &key_g);
+    assert(!pthread_key_delete(key_g));
+}
+
 void *test_tls_destructors(void *arg) {
     (void)arg;
     assert(!pthread_key_create(&key_a, drop_key_a));
     assert(!pthread_key_create(&key_b, drop_key_b));
+    assert(!pthread_key_create(&key_c, drop_unreachable));
+    assert(!pthread_key_create(&key_d, drop_key_d));
+    assert(!pthread_key_create(&key_e, drop_unreachable));
     assert(!pthread_setspecific(key_a, (void *)0xaaaa));
     assert(!pthread_setspecific(key_b, (void *)0xbbbb));
+    assert(!pthread_setspecific(key_c, (void *)0xcccc));
+    assert(!pthread_setspecific(key_d, (void *)0xdddd));
+    assert(!pthread_key_delete(key_c));
     return NULL;
 }
 
 int main(void) {
+    pthread_key_t key_f;
+    assert(!pthread_key_create(&key_f, NULL));
+    assert(!pthread_setspecific(key_f, &key_f));
+    assert(pthread_getspecific(key_f) == &key_f);
+    assert(!pthread_key_delete(key_f));
+
     pthread_t t1;
     assert(!pthread_create(&t1, NULL, test_tls_destructors, NULL));
     assert(!pthread_join(t1, NULL));
@@ -66,6 +95,5 @@ int main(void) {
     // of iterations will be `2 * PTHREAD_DESTRUCTOR_ITERATIONS`.
     assert((total_destructor_runs / 2) == PTHREAD_DESTRUCTOR_ITERATIONS);
 
-    assert(pthread_getspecific(PTHREAD_KEYS_MAX) == NULL);
     return EXIT_SUCCESS;
 }