diff --git a/include/libtorrent/peer_id.hpp b/include/libtorrent/peer_id.hpp
index d3bf624b7..e5a224bc4 100755
--- a/include/libtorrent/peer_id.hpp
+++ b/include/libtorrent/peer_id.hpp
@@ -38,6 +38,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <cassert>
 #include <cctype>
 #include <algorithm>
+#include <string>
 
 #include "libtorrent/config.hpp"
 
@@ -55,6 +56,12 @@ namespace libtorrent
 
 		big_number() {}
 
+		big_number(std::string const& s)
+		{
+			int sl = int(s.size()) < size ? int(s.size()) : size;
+			std::memcpy(m_number, &s[0], sl);
+		}
+
 		// when initialized with 0
 		big_number(private_pointer*) { clear(); }
 
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index cd906f8af..4d7cb2775 100755
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -1810,11 +1810,10 @@ namespace libtorrent { namespace detail
 			}
 
 			// verify info_hash
-			const std::string &hash = rd["info-hash"].string();
-			std::string real_hash((char*)info.info_hash().begin(), (char*)info.info_hash().end());
-			if (hash != real_hash)
+			sha1_hash hash = rd["info-hash"].string();
+			if (hash != info.info_hash())
 			{
-				error = "mismatching info-hash: " + hash;
+				error = "mismatching info-hash: " + boost::lexical_cast<std::string>(hash);
 				return;
 			}