diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 17e078615b0..c01f93c21ae 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1986,6 +1986,12 @@ util::Expected<void, std::string> PeerManagerImpl::FetchBlock(NodeId peer_id, co
 {
     if (m_chainman.m_blockman.LoadingBlocks()) return util::Unexpected{"Loading blocks ..."};
 
+    // The lock must be taken here before fetching Peer so another thread does
+    // not delete the CNodeState from under the current thread, causing an
+    // assertion failure in BlockRequested. This lock can be replaced with a
+    // net-specific lock when more of CNodeState is moved into Peer.
+    LOCK(cs_main);
+
     // Ensure this peer exists and hasn't been disconnected
     PeerRef peer = GetPeerRef(peer_id);
     if (peer == nullptr) return util::Unexpected{"Peer does not exist"};
@@ -1993,8 +1999,6 @@ util::Expected<void, std::string> PeerManagerImpl::FetchBlock(NodeId peer_id, co
     // Ignore pre-segwit peers
     if (!CanServeWitnesses(*peer)) return util::Unexpected{"Pre-SegWit peer"};
 
-    LOCK(cs_main);
-
     // Forget about all prior requests
     RemoveBlockRequest(block_index.GetBlockHash(), std::nullopt);