diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 7110078..0577825 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -87,7 +87,11 @@
 			nr_warps++;
 			__raw_spin_unlock(&sync_lock);
 		}
-
+	}
+	if (!(now-start)) {
+		printk("Warning: zero tsc calibration delta: %Ld [max: %Ld]\n",
+			now-start, end-start);
+		WARN_ON(1);
 	}
 }