diff --git a/src/ripple/app/main/Application.cpp b/src/ripple/app/main/Application.cpp
index d61eececfe..95e2f4bfa3 100644
--- a/src/ripple/app/main/Application.cpp
+++ b/src/ripple/app/main/Application.cpp
@@ -81,6 +81,7 @@
 #include <beast/core/detail/ci_char_traits.hpp>
 #include <boost/asio/signal_set.hpp>
 #include <boost/optional.hpp>
+#include <atomic>
 #include <fstream>
 
 namespace ripple {
@@ -250,11 +251,10 @@ private:
     class io_latency_sampler
     {
     private:
-        std::mutex mutable m_mutex;
         beast::insight::Event m_event;
         beast::Journal m_journal;
         beast::io_latency_probe <std::chrono::steady_clock> m_probe;
-        std::chrono::milliseconds m_lastSample;
+        std::atomic<std::chrono::milliseconds> lastSample_;
 
     public:
         io_latency_sampler (
@@ -265,6 +265,7 @@ private:
             : m_event (ev)
             , m_journal (journal)
             , m_probe (interval, ios)
+            , lastSample_ {}
         {
         }
 
@@ -280,10 +281,7 @@ private:
             using namespace std::chrono;
             auto const ms (ceil <std::chrono::milliseconds> (elapsed));
 
-            {
-                std::unique_lock <std::mutex> lock (m_mutex);
-                m_lastSample = ms;
-            }
+            lastSample_ = ms;
 
             if (ms.count() >= 10)
                 m_event.notify (ms);
@@ -297,8 +295,7 @@ private:
         std::chrono::milliseconds
         get () const
         {
-            std::unique_lock <std::mutex> lock (m_mutex);
-            return m_lastSample;
+            return lastSample_.load();
         }
 
         void
@@ -595,8 +592,6 @@ public:
 
     std::chrono::milliseconds getIOLatency () override
     {
-        std::unique_lock <std::mutex> m_IOLatencyLock;
-
         return m_io_latency_sampler.get ();
     }
 
diff --git a/src/ripple/nodestore/impl/DatabaseImp.h b/src/ripple/nodestore/impl/DatabaseImp.h
index 736accd9da..17f0063430 100644
--- a/src/ripple/nodestore/impl/DatabaseImp.h
+++ b/src/ripple/nodestore/impl/DatabaseImp.h
@@ -95,7 +95,7 @@ public:
     ~DatabaseImp ()
     {
         {
-            std::unique_lock <std::mutex> lock (m_readLock);
+            std::lock_guard <std::mutex> lock (m_readLock);
             m_readShut = true;
             m_readCondVar.notify_all ();
             m_readGenCondVar.notify_all ();
@@ -132,7 +132,7 @@ public:
 
         {
             // No. Post a read
-            std::unique_lock <std::mutex> lock (m_readLock);
+            std::lock_guard <std::mutex> lock (m_readLock);
             if (m_readSet.insert (hash).second)
                 m_readCondVar.notify_one ();
         }
diff --git a/src/ripple/overlay/tests/short_read.test.cpp b/src/ripple/overlay/tests/short_read.test.cpp
index 33459b3530..6ec7528cdf 100644
--- a/src/ripple/overlay/tests/short_read.test.cpp
+++ b/src/ripple/overlay/tests/short_read.test.cpp
@@ -124,14 +124,14 @@ private:
         void
         add (std::shared_ptr<Child> const& child)
         {
-            std::unique_lock<std::mutex> lock(mutex_);
+            std::lock_guard<std::mutex> lock(mutex_);
             list_.emplace(child.get(), child);
         }
 
         void
         remove (Child* child)
         {
-            std::unique_lock<std::mutex> lock(mutex_);
+            std::lock_guard<std::mutex> lock(mutex_);
             list_.erase(child);
             if (list_.empty())
                 cond_.notify_one();
@@ -142,7 +142,7 @@ private:
         {
             std::vector<std::shared_ptr<Child>> v;
             {
-                std::unique_lock<std::mutex> lock(mutex_);
+                std::lock_guard<std::mutex> lock(mutex_);
                 v.reserve(list_.size());
                 if (closed_)
                     return;
diff --git a/src/ripple/shamap/impl/SHAMapTreeNode.cpp b/src/ripple/shamap/impl/SHAMapTreeNode.cpp
index e456073d3e..be3e4fdf69 100644
--- a/src/ripple/shamap/impl/SHAMapTreeNode.cpp
+++ b/src/ripple/shamap/impl/SHAMapTreeNode.cpp
@@ -44,7 +44,7 @@ SHAMapInnerNode::clone(std::uint32_t seq) const
     p->mIsBranch = mIsBranch;
     p->mFullBelowGen = mFullBelowGen;
     p->mHashes = mHashes;
-    std::unique_lock <std::mutex> lock(childLock);
+    std::lock_guard <std::mutex> lock(childLock);
     for (int i = 0; i < 16; ++i)
     {
         p->mChildren[i] = mChildren[i];
@@ -63,7 +63,7 @@ SHAMapInnerNodeV2::clone(std::uint32_t seq) const
     p->mHashes = mHashes;
     p->common_ = common_;
     p->depth_ = depth_;
-    std::unique_lock <std::mutex> lock(childLock);
+    std::lock_guard <std::mutex> lock(childLock);
     for (int i = 0; i < 16; ++i)
     {
         p->mChildren[i] = mChildren[i];
@@ -679,7 +679,7 @@ SHAMapInnerNode::getChildPointer (int branch)
     assert (branch >= 0 && branch < 16);
     assert (isInner());
 
-    std::unique_lock <std::mutex> lock (childLock);
+    std::lock_guard <std::mutex> lock (childLock);
     return mChildren[branch].get ();
 }
 
@@ -689,7 +689,7 @@ SHAMapInnerNode::getChild (int branch)
     assert (branch >= 0 && branch < 16);
     assert (isInner());
 
-    std::unique_lock <std::mutex> lock (childLock);
+    std::lock_guard <std::mutex> lock (childLock);
     return mChildren[branch];
 }
 
@@ -701,7 +701,7 @@ SHAMapInnerNode::canonicalizeChild(int branch, std::shared_ptr<SHAMapAbstractNod
     assert (node);
     assert (node->getNodeHash() == mHashes[branch]);
 
-    std::unique_lock <std::mutex> lock (childLock);
+    std::lock_guard <std::mutex> lock (childLock);
     if (mChildren[branch])
     {
         // There is already a node hooked up, return it
@@ -725,7 +725,7 @@ SHAMapInnerNodeV2::canonicalizeChild(int branch, std::shared_ptr<SHAMapAbstractN
     assert (node);
     assert (node->getNodeHash() == mHashes[branch]);
 
-    std::unique_lock <std::mutex> lock (childLock);
+    std::lock_guard <std::mutex> lock (childLock);
     if (mChildren[branch])
     {
         // There is already a node hooked up, return it