diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1703,6 +1703,8 @@
 }
 
 UniValue MempoolInfoToJSON(const CTxMemPool &pool) {
+    // Make sure this call is atomic in the pool.
+    LOCK(pool.cs);
     UniValue ret(UniValue::VOBJ);
     ret.pushKV("loaded", pool.IsLoaded());
     ret.pushKV("size", (int64_t)pool.size());