diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c
index 47ecb5b..6a9a340 100644
--- a/hw/core/qdev-clock.c
+++ b/hw/core/qdev-clock.c
@@ -12,6 +12,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "hw/qdev-clock.h"
 #include "hw/qdev-core.h"
 #include "qapi/error.h"
@@ -153,6 +154,11 @@
     assert(name);
 
     ncl = qdev_get_clocklist(dev, name);
+    if (!ncl) {
+        error_report("Can not find clock-in '%s' for device type '%s'",
+                     name, object_get_typename(OBJECT(dev)));
+        abort();
+    }
     assert(!ncl->output);
 
     return ncl->clock;
@@ -165,6 +171,11 @@
     assert(name);
 
     ncl = qdev_get_clocklist(dev, name);
+    if (!ncl) {
+        error_report("Can not find clock-out '%s' for device type '%s'",
+                     name, object_get_typename(OBJECT(dev)));
+        abort();
+    }
     assert(ncl->output);
 
     return ncl->clock;