diff --git a/src/device/device_default.cpp b/src/device/device_default.cpp
index 30bb4a2e8..17b21c0ff 100644
--- a/src/device/device_default.cpp
+++ b/src/device/device_default.cpp
@@ -30,6 +30,7 @@
 
 
 
+#include <boost/thread/lock_guard.hpp>
 #include "device_default.hpp"
 #include "int-util.h"
 #include "crypto/wallet/crypto.h"
@@ -82,19 +83,32 @@ namespace hw {
             return true;
         }
 
+        // serialize mode access so callers cannot observe another wallet's transient signing mode
         bool  device_default::set_mode(device_mode mode) {
+            boost::lock_guard<boost::recursive_mutex> lock(device_locker);
             return device::set_mode(mode);
         }
 
+        device::device_mode device_default::get_mode() const {
+            boost::lock_guard<boost::recursive_mutex> lock(device_locker);
+            return device::get_mode();
+        }
+
         /* ======================================================================= */
         /*  LOCKER                                                                 */
         /* ======================================================================= */ 
     
-        void device_default::lock() { }
+        void device_default::lock() {
+            device_locker.lock();
+        }
 
-        bool device_default::try_lock() { return true; }
+        bool device_default::try_lock() {
+            return device_locker.try_lock();
+        }
 
-        void device_default::unlock() { }
+        void device_default::unlock() {
+            device_locker.unlock();
+        }
 
         /* ======================================================================= */
         /*                             WALLET & ADDRESS                            */
diff --git a/src/device/device_default.hpp b/src/device/device_default.hpp
index 9c8dbb099..28984c78f 100644
--- a/src/device/device_default.hpp
+++ b/src/device/device_default.hpp
@@ -29,6 +29,7 @@
 
 #pragma once
 
+#include <boost/thread/recursive_mutex.hpp>
 #include "device.hpp"
 
 namespace hw {
@@ -60,6 +61,7 @@ namespace hw {
             bool disconnect() override;
  
             bool set_mode(device_mode mode) override;
+            device_mode get_mode() const override;
 
             device_type get_type() const override {return device_type::SOFTWARE;};
 
@@ -141,6 +143,10 @@ namespace hw {
             bool clsag_sign(const rct::key &c, const rct::key &a, const rct::key &p, const rct::key &z, const rct::key &mu_P, const rct::key &mu_C, rct::key &s) override;
 
             bool  close_tx(void) override;
+
+        private:
+            // Locker for concurrent access
+            mutable boost::recursive_mutex device_locker;
         };
 
     }