diff --git a/src/rpc/rpc_payment.cpp b/src/rpc/rpc_payment.cpp
index 2b9c19f57..6cd52523f 100644
--- a/src/rpc/rpc_payment.cpp
+++ b/src/rpc/rpc_payment.cpp
@@ -92,6 +92,7 @@ namespace cryptonote
 
   uint64_t rpc_payment::balance(const crypto::public_key &client, int64_t delta)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     client_info &info = m_client_info[client]; // creates if not found
     uint64_t credits = info.credits;
     if (delta > 0 && credits > std::numeric_limits<uint64_t>::max() - delta)
@@ -107,6 +108,7 @@ namespace cryptonote
 
   bool rpc_payment::pay(const crypto::public_key &client, uint64_t ts, uint64_t payment, const std::string &rpc, bool same_ts, uint64_t &credits)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     client_info &info = m_client_info[client]; // creates if not found
     if (ts < info.last_request_timestamp || (ts == info.last_request_timestamp && !same_ts))
     {
@@ -130,6 +132,7 @@ namespace cryptonote
 
   bool rpc_payment::get_info(const crypto::public_key &client, const std::function<bool(const cryptonote::blobdata&, cryptonote::block&, uint64_t &seed_height, crypto::hash &seed_hash)> &get_block_template, cryptonote::blobdata &hashing_blob, uint64_t &seed_height, crypto::hash &seed_hash, const crypto::hash &top, uint64_t &diff, uint64_t &credits_per_hash_found, uint64_t &credits, uint32_t &cookie)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     client_info &info = m_client_info[client]; // creates if not found
     const uint64_t now = time(NULL);
     bool need_template = top != info.top || now >= info.block_template_update_time + STALE_THRESHOLD;
@@ -180,6 +183,7 @@ namespace cryptonote
 
   bool rpc_payment::submit_nonce(const crypto::public_key &client, uint32_t nonce, const crypto::hash &top, int64_t &error_code, std::string &error_message, uint64_t &credits, crypto::hash &hash, cryptonote::block &block, uint32_t cookie, bool &stale)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     client_info &info = m_client_info[client]; // creates if not found
     if (cookie != info.cookie && cookie != info.cookie - 1)
     {
@@ -272,6 +276,7 @@ namespace cryptonote
 
   bool rpc_payment::foreach(const std::function<bool(const crypto::public_key &client, const client_info &info)> &f) const
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     for (std::unordered_map<crypto::public_key, client_info>::const_iterator i = m_client_info.begin(); i != m_client_info.end(); ++i)
     {
       if (!f(i->first, i->second))
@@ -283,6 +288,7 @@ namespace cryptonote
   bool rpc_payment::load(std::string directory)
   {
     TRY_ENTRY();
+    boost::lock_guard<boost::mutex> lock(mutex);
     m_directory = std::move(directory);
     std::string state_file_path = directory + "/" + RPC_PAYMENTS_DATA_FILENAME;
     MINFO("loading rpc payments data from " << state_file_path);
@@ -313,6 +319,7 @@ namespace cryptonote
   bool rpc_payment::store(const std::string &directory_) const
   {
     TRY_ENTRY();
+    boost::lock_guard<boost::mutex> lock(mutex);
     const std::string &directory = directory_.empty() ? m_directory : directory_;
     MDEBUG("storing rpc payments data to " << directory);
     if (!tools::create_directories_if_necessary(directory))
@@ -345,6 +352,7 @@ namespace cryptonote
 
   unsigned int rpc_payment::flush_by_age(time_t seconds)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     unsigned int count = 0;
     const time_t now = time(NULL);
     time_t seconds0 = seconds;
@@ -372,6 +380,7 @@ namespace cryptonote
 
   uint64_t rpc_payment::get_hashes(unsigned int seconds) const
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     const uint64_t now = time(NULL);
     uint64_t hashes = 0;
     for (std::map<uint64_t, uint64_t>::const_reverse_iterator i = m_hashrate.crbegin(); i != m_hashrate.crend(); ++i)
@@ -385,6 +394,7 @@ namespace cryptonote
 
   void rpc_payment::prune_hashrate(unsigned int seconds)
   {
+    boost::lock_guard<boost::mutex> lock(mutex);
     const uint64_t now = time(NULL);
     std::map<uint64_t, uint64_t>::iterator i;
     for (i = m_hashrate.begin(); i != m_hashrate.end(); ++i)
diff --git a/src/rpc/rpc_payment.h b/src/rpc/rpc_payment.h
index f6832fd34..20117985f 100644
--- a/src/rpc/rpc_payment.h
+++ b/src/rpc/rpc_payment.h
@@ -31,6 +31,7 @@
 #include <string>
 #include <unordered_set>
 #include <unordered_map>
+#include <boost/thread/mutex.hpp>
 #include <boost/serialization/version.hpp>
 #include "cryptonote_basic/blobdatatype.h"
 #include "cryptonote_basic/cryptonote_basic.h"
@@ -139,6 +140,7 @@ namespace cryptonote
     uint64_t m_nonces_stale;
     uint64_t m_nonces_bad;
     uint64_t m_nonces_dupe;
+    mutable boost::mutex mutex;
   };
 }