diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 0c11c2b020..3f9705271f 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1680,6 +1680,8 @@ static UniValue getchaintips(const JSONRPCRequest& request)
 
 UniValue MempoolInfoToJSON(const CTxMemPool& pool)
 {
+    // Make sure this call is atomic in the pool.
+    LOCK(pool.cs);
     UniValue ret(UniValue::VOBJ);
     ret.pushKV("size", (int64_t)pool.size());
     ret.pushKV("bytes", (int64_t)pool.GetTotalTxSize());