diff --git a/src/util/system.h b/src/util/system.h
--- a/src/util/system.h
+++ b/src/util/system.h
@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2016 The Bitcoin Core developers
+// Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -26,13 +26,11 @@
 
 #include <boost/thread/condition_variable.hpp> // for boost::thread_interrupted
 
-#include <atomic>
 #include <cstdint>
 #include <exception>
 #include <map>
 #include <set>
 #include <string>
-#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -84,6 +82,7 @@
 // The blocks directory is always net specific.
 const fs::path &GetBlocksDir();
 const fs::path &GetDataDir(bool fNetSpecific = true);
+/** Tests only */
 void ClearDatadirCache();
 fs::path GetConfigFile(const std::string &confPath);
 #ifdef WIN32
diff --git a/src/util/system.cpp b/src/util/system.cpp
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2016 The Bitcoin Core developers
+// Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -803,15 +803,14 @@
 static fs::path g_blocks_path_cache_net_specific;
 static fs::path pathCached;
 static fs::path pathCachedNetSpecific;
-static CCriticalSection csPathCached;
+static RecursiveMutex csPathCached;
 
 const fs::path &GetBlocksDir() {
     LOCK(csPathCached);
-
     fs::path &path = g_blocks_path_cache_net_specific;
 
-    // This can be called during exceptions by LogPrintf(), so we cache the
-    // value so we don't have to do memory allocations after that.
+    // Cache the path to avoid calling fs::create_directories on every call of
+    // this function
     if (!path.empty()) {
         return path;
     }
@@ -834,11 +833,10 @@
 
 const fs::path &GetDataDir(bool fNetSpecific) {
     LOCK(csPathCached);
-
     fs::path &path = fNetSpecific ? pathCachedNetSpecific : pathCached;
 
-    // This can be called during exceptions by LogPrintf(), so we cache the
-    // value so we don't have to do memory allocations after that.
+    // Cache the path to avoid calling fs::create_directories on every call of
+    // this function
     if (!path.empty()) {
         return path;
     }