diff --git a/src/test/dbwrapper_tests.cpp b/src/test/dbwrapper_tests.cpp
--- a/src/test/dbwrapper_tests.cpp
+++ b/src/test/dbwrapper_tests.cpp
@@ -270,7 +270,7 @@
     CDBWrapper dbw(ph, (1 << 20), true, false, false);
     for (int x = 0x00; x < 10; ++x) {
         for (int y = 0; y < 10; y++) {
-            sprintf(buf, "%d", x);
+            snprintf(buf, sizeof(buf), "%d", x);
             StringContentsSerializer key(buf);
             for (int z = 0; z < y; z++)
                 key += key;
@@ -282,12 +282,12 @@
     std::unique_ptr<CDBIterator> it(
         const_cast<CDBWrapper &>(dbw).NewIterator());
     for (int seek_start : {0, 5}) {
-        sprintf(buf, "%d", seek_start);
+        snprintf(buf, sizeof(buf), "%d", seek_start);
         StringContentsSerializer seek_key(buf);
         it->Seek(seek_key);
         for (int x = seek_start; x < 10; ++x) {
             for (int y = 0; y < 10; y++) {
-                sprintf(buf, "%d", x);
+                snprintf(buf, sizeof(buf), "%d", x);
                 std::string exp_key(buf);
                 for (int z = 0; z < y; z++)
                     exp_key += exp_key;
diff --git a/src/uint256.cpp b/src/uint256.cpp
--- a/src/uint256.cpp
+++ b/src/uint256.cpp
@@ -17,11 +17,8 @@
 }
 
 template <unsigned int BITS> std::string base_blob<BITS>::GetHex() const {
-    char psz[sizeof(data) * 2 + 1];
-    for (size_t i = 0; i < sizeof(data); i++) {
-        sprintf(psz + i * 2, "%02x", data[sizeof(data) - i - 1]);
-    }
-    return std::string(psz, psz + sizeof(data) * 2);
+    return HexStr(std::reverse_iterator<const uint8_t *>(data + sizeof(data)),
+                  std::reverse_iterator<const uint8_t *>(data));
 }
 
 template <unsigned int BITS> void base_blob<BITS>::SetHex(const char *psz) {