diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
index 1243823da..2e6136357 100644
--- a/src/arith_uint256.cpp
+++ b/src/arith_uint256.cpp
@@ -7,6 +7,7 @@
 
 #include "uint256.h"
 #include "utilstrencodings.h"
+#include "crypto/common.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -246,14 +247,14 @@ uint32_t arith_uint256::GetCompact(bool fNegative) const
 uint256 ArithToUint256(const arith_uint256 &a)
 {
     uint256 b;
-    // TODO: needs bswap32 on big-endian
-    memcpy(b.begin(), a.pn, a.size());
+    for(int x=0; x<a.WIDTH; ++x)
+        WriteLE32(b.begin() + x*4, a.pn[x]);
     return b;
 }
 arith_uint256 UintToArith256(const uint256 &a)
 {
     arith_uint256 b;
-    // TODO: needs bswap32 on big-endian
-    memcpy(b.pn, a.begin(), a.size());
+    for(int x=0; x<b.WIDTH; ++x)
+        b.pn[x] = ReadLE32(a.begin() + x*4);
     return b;
 }