diff --git a/src/main.cpp b/src/main.cpp
index c54fa6523..a1fe6c07b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -3488,7 +3488,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         return true;
     }
 
-    State(pfrom->GetId())->nLastBlockProcess = GetTimeMicros();
+    {
+        LOCK(cs_main);
+        State(pfrom->GetId())->nLastBlockProcess = GetTimeMicros();
+    }