diff --git a/gio/win32/gwinhttpfile.c b/gio/win32/gwinhttpfile.c
index a4709ed4d..7e72b9f4e 100644
--- a/gio/win32/gwinhttpfile.c
+++ b/gio/win32/gwinhttpfile.c
@@ -387,12 +387,12 @@ g_winhttp_file_resolve_relative_path (GFile      *file,
   child = g_object_new (G_TYPE_WINHTTP_FILE, NULL);
   child->vfs = winhttp_file->vfs;
   child->url = winhttp_file->url;
-  child->url.lpszScheme = g_memdup (winhttp_file->url.lpszScheme, winhttp_file->url.dwSchemeLength*2);
-  child->url.lpszHostName = g_memdup (winhttp_file->url.lpszHostName, winhttp_file->url.dwHostNameLength*2);
-  child->url.lpszUserName = g_memdup (winhttp_file->url.lpszUserName, winhttp_file->url.dwUserNameLength*2);
-  child->url.lpszPassword = g_memdup (winhttp_file->url.lpszPassword, winhttp_file->url.dwPasswordLength*2);
+  child->url.lpszScheme = g_memdup (winhttp_file->url.lpszScheme, (winhttp_file->url.dwSchemeLength+1)*2);
+  child->url.lpszHostName = g_memdup (winhttp_file->url.lpszHostName, (winhttp_file->url.dwHostNameLength+1)*2);
+  child->url.lpszUserName = g_memdup (winhttp_file->url.lpszUserName, (winhttp_file->url.dwUserNameLength+1)*2);
+  child->url.lpszPassword = g_memdup (winhttp_file->url.lpszPassword, (winhttp_file->url.dwPasswordLength+1)*2);
   child->url.lpszUrlPath = wnew_path;
-  child->url.dwUrlPathLength = 2*(wcslen (wnew_path)+1);
+  child->url.dwUrlPathLength = wcslen (wnew_path);
   child->url.lpszExtraInfo = NULL;
   child->url.dwExtraInfoLength = 0;