diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
index 0dba429a8..f0b6a6a3b 100644
--- a/src/arith_uint256.cpp
+++ b/src/arith_uint256.cpp
@@ -5,6 +5,7 @@
 
 #include "arith_uint256.h"
 
+#include "uint256.h"
 #include "utilstrencodings.h"
 
 #include <stdio.h>
@@ -355,3 +356,18 @@ uint64_t arith_uint256::GetHash(const arith_uint256& salt) const
 
     return ((((uint64_t)b) << 32) | c);
 }
+
+uint256 ArithToUint256(const arith_uint256 &a)
+{
+    uint256 b;
+    // TODO: needs bswap32 on big-endian
+    memcpy(b.begin(), a.pn, a.size());
+    return b;
+}
+arith_uint256 UintToArith256(const uint256 &a)
+{
+    arith_uint256 b;
+    // TODO: needs bswap32 on big-endian
+    memcpy(b.pn, a.begin(), a.size());
+    return b;
+}
diff --git a/src/arith_uint256.h b/src/arith_uint256.h
index 9e32b124c..5cb04f3c3 100644
--- a/src/arith_uint256.h
+++ b/src/arith_uint256.h
@@ -13,6 +13,8 @@
 #include <string>
 #include <vector>
 
+class uint256;
+
 class uint_error : public std::runtime_error {
 public:
     explicit uint_error(const std::string& str) : std::runtime_error(str) {}
@@ -345,6 +347,12 @@ public:
     uint32_t GetCompact(bool fNegative = false) const;
 
     uint64_t GetHash(const arith_uint256& salt) const;
+
+    friend uint256 ArithToUint256(const arith_uint256 &);
+    friend arith_uint256 UintToArith256(const uint256 &);
 };
 
+uint256 ArithToUint256(const arith_uint256 &);
+arith_uint256 UintToArith256(const uint256 &);
+
 #endif // BITCOIN_UINT256_H