diff --git a/system/qtest.c b/system/qtest.c
index 99ef2042f6..e68ed0f2a8 100644
--- a/system/qtest.c
+++ b/system/qtest.c
@@ -78,6 +78,11 @@ static void *qtest_server_send_opaque;
  * let you adjust the value of the clock (monotonically).  All the commands
  * return the current value of the clock in nanoseconds.
  *
+ * If the commands FAIL then time wasn't advanced which is likely
+ * because the machine was in a paused state or no timer events exist
+ * in the future. This will cause qtest to abort and the test will
+ * need to check its assumptions.
+ *
  * .. code-block:: none
  *
  *  > clock_step
@@ -710,7 +715,8 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
             qtest_sendf(chr, "OK little\n");
         }
     } else if (qtest_enabled() && strcmp(words[0], "clock_step") == 0) {
-        int64_t ns;
+        int64_t old_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        int64_t ns, new_ns;
 
         if (words[1]) {
             int ret = qemu_strtoi64(words[1], NULL, 0, &ns);
@@ -719,11 +725,10 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
             ns = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
                                             QEMU_TIMER_ATTR_ALL);
         }
-        qemu_clock_advance_virtual_time(
-            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns);
+        new_ns = qemu_clock_advance_virtual_time(old_ns + ns);
         qtest_send_prefix(chr);
-        qtest_sendf(chr, "OK %"PRIi64"\n",
-                    (int64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+        qtest_sendf(chr, "%s %"PRIi64"\n",
+                    new_ns > old_ns ? "OK" : "FAIL", new_ns);
     } else if (strcmp(words[0], "module_load") == 0) {
         Error *local_err = NULL;
         int rv;
@@ -740,16 +745,16 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
             qtest_sendf(chr, "FAIL\n");
         }
     } else if (qtest_enabled() && strcmp(words[0], "clock_set") == 0) {
-        int64_t ns;
+        int64_t ns, new_ns;
         int ret;
 
         g_assert(words[1]);
         ret = qemu_strtoi64(words[1], NULL, 0, &ns);
         g_assert(ret == 0);
-        qemu_clock_advance_virtual_time(ns);
+        new_ns = qemu_clock_advance_virtual_time(ns);
         qtest_send_prefix(chr);
-        qtest_sendf(chr, "OK %"PRIi64"\n",
-                    (int64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+        qtest_sendf(chr, "%s %"PRIi64"\n",
+                    new_ns == ns ? "OK" : "FAIL", new_ns);
     } else if (process_command_cb && process_command_cb(chr, words)) {
         /* Command got consumed by the callback handler */
     } else {