diff --git a/src/net_processing.cpp b/src/net_processing.cpp
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1240,7 +1240,7 @@
     /**
      * Height of the highest block announced using BIP 152 high-bandwidth mode.
      */
-    int m_highest_fast_announce{0};
+    int m_highest_fast_announce GUARDED_BY(::cs_main){0};
 
     /** Have we requested this block from a peer */
     bool IsBlockRequested(const BlockHash &hash)