diff --git a/src/main.cpp b/src/main.cpp
index 463ac6177..0b5455858 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -3379,7 +3379,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         return true;
     }
 
-    State(pfrom->GetId())->nLastBlockProcess = GetTimeMicros();
+    {
+        LOCK(cs_main);
+        State(pfrom->GetId())->nLastBlockProcess = GetTimeMicros();
+    }