diff --git a/include/libtorrent/bitfield.hpp b/include/libtorrent/bitfield.hpp
index bd53086bb..f970c7257 100644
--- a/include/libtorrent/bitfield.hpp
+++ b/include/libtorrent/bitfield.hpp
@@ -222,6 +222,7 @@ namespace libtorrent
 	
 		void resize(int bits)
 		{
+			TORRENT_ASSERT(bits >= 0);
 			const int b = (bits + 7) / 8;
 			if (m_bytes)
 			{
@@ -238,7 +239,7 @@ namespace libtorrent
 					m_own = true;
 				}
 			}
-			else
+			else if (bits > 0)
 			{
 				m_bytes = (unsigned char*)std::malloc(b);
 				m_own = true;