diff --git a/include/libtorrent/escape_string.hpp b/include/libtorrent/escape_string.hpp
index 439be40e5..9fd8156a5 100644
--- a/include/libtorrent/escape_string.hpp
+++ b/include/libtorrent/escape_string.hpp
@@ -72,7 +72,7 @@ namespace libtorrent
 	TORRENT_EXPORT std::string base32decode(std::string const& s);
 
 	TORRENT_EXPORT std::string url_has_argument(
-		std::string const& url, std::string argument, int* out_pos = 0);
+		std::string const& url, std::string argument, std::string::size_type* out_pos = 0);
 
 	// replaces \ with /
 	TORRENT_EXPORT void convert_path_to_posix(std::string& path);
diff --git a/src/escape_string.cpp b/src/escape_string.cpp
index 68b54ae57..a3185eb64 100644
--- a/src/escape_string.cpp
+++ b/src/escape_string.cpp
@@ -473,7 +473,7 @@ namespace libtorrent
 	}
 
 	std::string url_has_argument(
-		std::string const& url, std::string argument, int* out_pos)
+		std::string const& url, std::string argument, std::string::size_type* out_pos)
 	{
 		size_t i = url.find('?');
 		if (i == std::string::npos) return std::string();
diff --git a/src/magnet_uri.cpp b/src/magnet_uri.cpp
index 81982ca63..f379c3023 100644
--- a/src/magnet_uri.cpp
+++ b/src/magnet_uri.cpp
@@ -146,7 +146,7 @@ namespace libtorrent
 		error_code e;
 		std::string display_name = url_has_argument(uri, "dn");
 		if (!display_name.empty()) name = unescape_string(display_name.c_str(), e);
-		int pos = std::string::npos;
+		std::string::size_type pos = std::string::npos;
 		std::string tracker_string = url_has_argument(uri, "tr", &pos);
 		if (!tracker_string.empty()) tracker = unescape_string(tracker_string.c_str(), e);