diff --git a/src/crypto/crypto.cpp b/src/crypto/crypto.cpp
index 494027560..4937a234a 100644
--- a/src/crypto/crypto.cpp
+++ b/src/crypto/crypto.cpp
@@ -70,8 +70,6 @@ namespace crypto {
 #include "random.h"
   }
 
-  boost::mutex random_lock;
-
   static inline unsigned char *operator &(ec_point &point) {
     return &reinterpret_cast<unsigned char &>(point);
   }
@@ -88,6 +86,13 @@ namespace crypto {
     return &reinterpret_cast<const unsigned char &>(scalar);
   }
 
+  void generate_random_bytes_thread_safe(size_t N, uint8_t *bytes)
+  {
+    static boost::mutex random_lock;
+    boost::lock_guard<boost::mutex> lock(random_lock);
+    generate_random_bytes_not_thread_safe(N, bytes);
+  }
+
   /* generate a random 32-byte (256-bit) integer and copy it to res */
   static inline void random_scalar_not_thread_safe(ec_scalar &res) {
     unsigned char tmp[64];
@@ -96,8 +101,10 @@ namespace crypto {
     memcpy(&res, tmp, 32);
   }
   static inline void random_scalar(ec_scalar &res) {
-    boost::lock_guard<boost::mutex> lock(random_lock);
-    random_scalar_not_thread_safe(res);
+    unsigned char tmp[64];
+    generate_random_bytes_thread_safe(64, tmp);
+    sc_reduce(tmp);
+    memcpy(&res, tmp, 32);
   }
 
   void hash_to_scalar(const void *data, size_t length, ec_scalar &res) {
diff --git a/src/crypto/crypto.h b/src/crypto/crypto.h
index 81ebfb9e2..9ea0f2ec0 100644
--- a/src/crypto/crypto.h
+++ b/src/crypto/crypto.h
@@ -53,8 +53,6 @@ namespace crypto {
 #include "random.h"
   }
 
-  extern boost::mutex random_lock;
-
 #pragma pack(push, 1)
   POD_CLASS ec_point {
     char data[32];
@@ -149,11 +147,12 @@ namespace crypto {
       const public_key *const *, std::size_t, const signature *);
   };
 
+  void generate_random_bytes_thread_safe(size_t N, uint8_t *bytes);
+
   /* Generate N random bytes
    */
   inline void rand(size_t N, uint8_t *bytes) {
-    boost::lock_guard<boost::mutex> lock(random_lock);
-    generate_random_bytes_not_thread_safe(N, bytes);
+    generate_random_bytes_thread_safe(N, bytes);
   }
 
   /* Generate a value filled with random bytes.
@@ -161,8 +160,7 @@ namespace crypto {
   template<typename T>
   typename std::enable_if<std::is_pod<T>::value, T>::type rand() {
     typename std::remove_cv<T>::type res;
-    boost::lock_guard<boost::mutex> lock(random_lock);
-    generate_random_bytes_not_thread_safe(sizeof(T), &res);
+    generate_random_bytes_thread_safe(sizeof(T), (uint8_t*)&res);
     return res;
   }