diff --git a/include/fc/uint128.hpp b/include/fc/uint128.hpp
index 08c3cc1..cbee51b 100644
--- a/include/fc/uint128.hpp
+++ b/include/fc/uint128.hpp
@@ -3,6 +3,8 @@
 #include <stdint.h>
 #include <string>
 
+#include <fc/exception/exception.hpp>
+
 #ifdef _MSC_VER
   #pragma warning (push)
   #pragma warning (disable : 4244)
@@ -74,8 +76,19 @@ namespace fc
       friend bool    operator >=  ( const uint128& l, const uint128& r ) { return l == r || l > r; }
       friend bool    operator <=  ( const uint128& l, const uint128& r ) { return l == r || l < r; }
 
-      uint32_t to_integer()const { return (uint32_t)lo; }
-      uint64_t to_uint64()const { return lo; }
+      uint32_t to_integer()const
+      {
+          FC_ASSERT( hi == 0 );
+          uint32_t lo32 = (uint32_t) lo;
+          FC_ASSERT( lo == lo32 );
+          return lo32;
+      }
+      uint64_t to_uint64()const
+      {
+          FC_ASSERT( hi == 0 );
+          return lo;
+      }
+      uint32_t low_32_bits()const { return (uint32_t) lo; }
       uint64_t low_bits()const  { return lo; }
       uint64_t high_bits()const { return hi; }