diff --git a/src/ripple/nodestore/impl/DatabaseShardImp.cpp b/src/ripple/nodestore/impl/DatabaseShardImp.cpp
index 94d9a457dce..38aa231a9db 100644
--- a/src/ripple/nodestore/impl/DatabaseShardImp.cpp
+++ b/src/ripple/nodestore/impl/DatabaseShardImp.cpp
@@ -256,39 +256,47 @@ DatabaseShardImp::init()
 boost::optional<std::uint32_t>
 DatabaseShardImp::prepareLedger(std::uint32_t validLedgerSeq)
 {
-    std::lock_guard lock(mutex_);
-    assert(init_);
+    boost::optional<std::uint32_t> shardIndex;
 
-    if (acquireIndex_ != 0)
     {
-        if (auto it {shards_.find(acquireIndex_)}; it != shards_.end())
-            return it->second.shard->prepare();
-        assert(false);
-        return boost::none;
-    }
+        std::lock_guard lock(mutex_);
+        assert(init_);
 
-    if (!canAdd_)
-        return boost::none;
+        if (acquireIndex_ != 0)
+        {
+            if (auto it {shards_.find(acquireIndex_)}; it != shards_.end())
+                return it->second.shard->prepare();
+            assert(false);
+            return boost::none;
+        }
 
-    // Check available storage space
-    if (fileSz_ + avgShardFileSz_ > maxFileSz_)
-    {
-        JLOG(j_.debug()) << "maximum storage size reached";
-        canAdd_ = false;
-        return boost::none;
-    }
-    if (avgShardFileSz_ > available())
-    {
-        JLOG(j_.error()) << "insufficient storage space available";
-        canAdd_ = false;
-        return boost::none;
+        if (!canAdd_)
+            return boost::none;
+
+        // Check available storage space
+        if (fileSz_ + avgShardFileSz_ > maxFileSz_)
+        {
+            JLOG(j_.debug()) << "maximum storage size reached";
+            canAdd_ = false;
+            return boost::none;
+        }
+        if (avgShardFileSz_ > available())
+        {
+            JLOG(j_.error()) << "insufficient storage space available";
+            canAdd_ = false;
+            return boost::none;
+        }
+
+        shardIndex = findAcquireIndex(validLedgerSeq, lock);
     }
 
-    auto const shardIndex {findAcquireIndex(validLedgerSeq, lock)};
     if (!shardIndex)
     {
         JLOG(j_.debug()) << "no new shards to add";
-        canAdd_ = false;
+        {
+            std::lock_guard lock(mutex_);
+            canAdd_ = false;
+        }
         return boost::none;
     }
 
@@ -297,10 +305,13 @@ DatabaseShardImp::prepareLedger(std::uint32_t validLedgerSeq)
         return boost::none;
 
     auto const seq {shard->prepare()};
-    shards_.emplace(
-        *shardIndex,
-        ShardInfo(std::move(shard), ShardInfo::State::acquire));
-    acquireIndex_ = *shardIndex;
+    {
+        std::lock_guard lock(mutex_);
+        shards_.emplace(
+            *shardIndex,
+            ShardInfo(std::move(shard), ShardInfo::State::acquire));
+        acquireIndex_ = *shardIndex;
+    }
     return seq;
 }