diff --git a/nse_nsock.cc b/nse_nsock.cc
index 75a7c8b08..96e659b92 100644
--- a/nse_nsock.cc
+++ b/nse_nsock.cc
@@ -757,7 +757,7 @@ static int l_set_timeout (lua_State *L)
 {
   nse_nsock_udata *nu = check_nsock_udata(L, 1, 0);
   nu->timeout = luaL_checkint(L, 2);
-  if ((int) nu->timeout < -1)
+  if ((int) nu->timeout < -1) /* -1 is no timeout */
     return luaL_error(L, "Negative timeout: %d", nu->timeout);
   return success(L);
 }