diff --git a/include/fc/crypto/sha224.hpp b/include/fc/crypto/sha224.hpp
index 9ea9290..3411e7c 100644
--- a/include/fc/crypto/sha224.hpp
+++ b/include/fc/crypto/sha224.hpp
@@ -84,3 +84,5 @@ namespace std
        }
     };
 }
+#include <fc/reflect/reflect.hpp>
+FC_REFLECT_TYPENAME( fc::sha224 )
diff --git a/include/fc/exception/exception.hpp b/include/fc/exception/exception.hpp
index 1457214..baffcdf 100644
--- a/include/fc/exception/exception.hpp
+++ b/include/fc/exception/exception.hpp
@@ -33,7 +33,9 @@ namespace fc
        unknown_host_exception_code       = 15,
        null_optional_code                = 16,
        udt_error_code                    = 17,
-       aes_error_code                    = 18
+       aes_error_code                    = 18,
+       overflow_code                     = 19,
+       underflow_code                    = 20
    };
 
    /**
@@ -285,6 +287,8 @@ namespace fc
   FC_DECLARE_EXCEPTION( null_optional, null_optional_code, "null optional" );
   FC_DECLARE_EXCEPTION( udt_exception, udt_error_code, "UDT error" );
   FC_DECLARE_EXCEPTION( aes_exception, aes_error_code, "AES error" );
+  FC_DECLARE_EXCEPTION( overflow_exception, overflow_code, "Integer Overflow" );
+  FC_DECLARE_EXCEPTION( underflow_exception, underflow_code, "Integer Underflow" );
 
   std::string except_str();
 
diff --git a/include/fc/io/raw.hpp b/include/fc/io/raw.hpp
index 7e58330..3d3c0b5 100644
--- a/include/fc/io/raw.hpp
+++ b/include/fc/io/raw.hpp
@@ -9,6 +9,7 @@
 #include <fc/time.hpp>
 #include <fc/filesystem.hpp>
 #include <fc/exception/exception.hpp>
+#include <fc/safe.hpp>
 #include <map>
 
 #define MAX_ARRAY_ALLOC_SIZE (1024*1024*10) 
@@ -162,11 +163,24 @@ namespace fc {
       vi.value = static_cast<uint32_t>(v);
     }
 
+    template<typename Stream, typename T> inline void unpack( Stream& s, const T& vi ) 
+    {
+       T tmp;
+       unpack( s, tmp );
+       FC_ASSERT( vi == tmp );
+    }
+
     template<typename Stream> inline void pack( Stream& s, const char* v ) { pack( s, fc::string(v) ); }
 
+    template<typename Stream, typename T> 
+    void pack( Stream& s, const safe<T>& v ) { pack( s, v.value ); }
+
+    template<typename Stream, typename T>
+    void unpack( Stream& s, fc::safe<T>& v ) { unpack( s, v.value ); }
+
     // optional
     template<typename Stream, typename T> 
-    inline void pack( Stream& s, const fc::optional<T>& v ) {
+    void pack( Stream& s, const fc::optional<T>& v ) {
       pack( s, bool(!!v) );
       if( !!v ) pack( s, *v );
     }
diff --git a/include/fc/io/raw_fwd.hpp b/include/fc/io/raw_fwd.hpp
index 922782e..69247f9 100644
--- a/include/fc/io/raw_fwd.hpp
+++ b/include/fc/io/raw_fwd.hpp
@@ -1,6 +1,7 @@
 #pragma once
 #include <fc/io/varint.hpp>
 #include <fc/array.hpp>
+#include <fc/safe.hpp>
 #include <vector>
 #include <string>
 #include <unordered_set>
@@ -48,7 +49,10 @@ namespace fc {
 
 
     template<typename Stream, typename T> void unpack( Stream& s, fc::optional<T>& v ); 
+    template<typename Stream, typename T> void unpack( Stream& s, const T& v ); 
     template<typename Stream, typename T> void pack( Stream& s, const fc::optional<T>& v );
+    template<typename Stream, typename T> void pack( Stream& s, const safe<T>& v );
+    template<typename Stream, typename T> void unpack( Stream& s, fc::safe<T>& v );
 
     template<typename Stream> void unpack( Stream& s, time_point& ); 
     template<typename Stream> void pack( Stream& s, const time_point& );
diff --git a/include/fc/safe.hpp b/include/fc/safe.hpp
new file mode 100644
index 0000000..be606c3
--- /dev/null
+++ b/include/fc/safe.hpp
@@ -0,0 +1,64 @@
+#pragma once
+#include <fc/exception/exception.hpp>
+
+namespace fc {
+
+   /**
+    *  This type is designed to provide automatic checks for
+    *  integer overflow and default initialization. It will
+    *  throw an exception on overflow conditions.
+    */
+   template<typename T>
+   struct safe 
+   {
+      template<typename O>
+      safe( O o ):value(o){}
+      safe(){}
+      safe( const safe& o ):value(o.value){}
+
+
+      safe& operator += (  const safe& b )
+      {
+         if( b.value > 0 && value > (std::numeric_limits<T>::max() - b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (*this)(b) );
+         if( b.value < 0 && value < (std::numeric_limits<T>::min() - b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (*this)(b) );
+         value += b.value;
+         return *this;
+      }
+      friend safe operator + ( const safe& a, const safe& b )
+      {
+         if( b.value > 0 && a.value > std::numeric_limits<T>::max() - b.value ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
+         if( b.value < 0 && a.value < std::numeric_limits<T>::min() - b.value ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
+         return safe(a.value+b.value);
+      }
+      safe& operator -= (  const safe& b ) { return *this += safe(-b.value); }
+      safe operator -()const{ return safe(-value); }
+
+      friend safe operator - ( const safe& a, const safe& b )
+      {
+         safe tmp(a); tmp -= b; return tmp;
+      }
+
+      friend bool operator == ( const safe& a, const safe& b )
+      {
+         return a.value == b.value;
+      }
+      friend bool operator < ( const safe& a, const safe& b )
+      {
+         return a.value < b.value;
+      }
+      friend bool operator > ( const safe& a, const safe& b )
+      {
+         return a.value > b.value;
+      }
+      friend bool operator >= ( const safe& a, const safe& b )
+      {
+         return a.value >= b.value;
+      }
+      friend bool operator <= ( const safe& a, const safe& b )
+      {
+         return a.value <= b.value;
+      }
+      T value = 0;
+   };
+
+} 
diff --git a/include/fc/variant.hpp b/include/fc/variant.hpp
index c9c2d29..995dc5a 100644
--- a/include/fc/variant.hpp
+++ b/include/fc/variant.hpp
@@ -30,11 +30,14 @@ namespace fc
    class time_point;
    class time_point_sec;
    class microseconds;
+   template<typename T> struct safe;
 
    struct blob { std::vector<char> data; };
 
    void to_variant( const blob& var,  variant& vo );
    void from_variant( const variant& var,  blob& vo );
+   template<typename T> void to_variant( const safe<T>& s, variant& v );
+   template<typename T> void from_variant( const variant& v, safe<T>& s );
 
    void to_variant( const uint8_t& var,  variant& vo );
    void from_variant( const variant& var,  uint8_t& vo );
@@ -111,6 +114,7 @@ namespace fc
    void from_variant( const variant& v, std::pair<A,B>& p );
 
 
+
    /**
     * @brief stores null, int64, uint64, double, bool, string, std::vector<variant>,
     *        and variant_object's.  
@@ -480,6 +484,11 @@ namespace fc
           from_variant( var, *vo );
       }
    }
+   template<typename T>
+   void to_variant( const safe<T>& s, variant& v ) { v = s.value; }
+
+   template<typename T>
+   void from_variant( const variant& v, safe<T>& s ) { s.value = v.as_uint64(); }
 
    variant operator + ( const variant& a, const variant& b );
    variant operator - ( const variant& a, const variant& b );
diff --git a/src/exception.cpp b/src/exception.cpp
index 15ce8da..922fad0 100644
--- a/src/exception.cpp
+++ b/src/exception.cpp
@@ -21,6 +21,8 @@ namespace fc
                            (null_optional)
                            (udt_exception)
                            (aes_exception)
+                           (overflow_exception)
+                           (underflow_exception)
                          )
 
    namespace detail