diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index cce2fd6acc..bd796579ee 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -620,11 +620,13 @@ static inline hwaddr cpu_get_phys_page_debug(CPUState *cpu, vaddr addr)
 static inline int cpu_asidx_from_attrs(CPUState *cpu, MemTxAttrs attrs)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
+    int ret = 0;
 
     if (cc->asidx_from_attrs) {
-        return cc->asidx_from_attrs(cpu, attrs);
+        ret = cc->asidx_from_attrs(cpu, attrs);
+        assert(ret < cpu->num_ases && ret >= 0);
     }
-    return 0;
+    return ret;
 }
 #endif