diff --git a/libraries/chain/include/graphene/chain/protocol/ext.hpp b/libraries/chain/include/graphene/chain/protocol/ext.hpp
index 366dcd63..7e8636f5 100644
--- a/libraries/chain/include/graphene/chain/protocol/ext.hpp
+++ b/libraries/chain/include/graphene/chain/protocol/ext.hpp
@@ -130,6 +130,7 @@ struct graphene_extension_unpack_visitor
 template< typename Stream, typename T >
 void operator>>( Stream& s, graphene::chain::extension<T>& value )
 {
+   value = graphene::chain::extension<T>();
    graphene_extension_unpack_visitor<Stream, T> vtor( s, value.value );
    fc::reflector<T>::visit( vtor );
    FC_ASSERT( vtor.count_left == 0 ); // unrecognized extension throws here
@@ -168,6 +169,7 @@ struct graphene_extension_from_variant_visitor
 template< typename T >
 void from_variant( const fc::variant& var, graphene::chain::extension<T>& value )
 {
+   value = graphene::chain::extension<T>();
    if( var.is_null() )
       return;
    if( var.is_array() )