diff --git a/libtransmission/net.c b/libtransmission/net.c
index fd5f37e65..ecc99aded 100644
--- a/libtransmission/net.c
+++ b/libtransmission/net.c
@@ -176,33 +176,11 @@ void tr_netSetTOS(tr_socket_t s, int tos, tr_address_type type)
     else if (type == TR_AF_INET6)
     {
 #if defined(IPV6_TCLASS) && !defined(_WIN32)
-
-        int dscp = 0;
-
-        switch (tos)
-        {
-        case 0x10:
-            dscp = 0x20; /* lowcost (CS1) */
-            break;
-
-        case 0x08:
-            dscp = 0x28; /* throughput (AF11) */
-            break;
-
-        case 0x04:
-            dscp = 0x04; /* reliability */
-            break;
-
-        case 0x02:
-            dscp = 0x30; /* low delay (AF12) */
-            break;
-        }
-
-        if (setsockopt(s, IPPROTO_IPV6, IPV6_TCLASS, (void const*)&dscp, sizeof(dscp)) == -1)
+        if (setsockopt(s, IPPROTO_IPV6, IPV6_TCLASS, (void const*)&tos, sizeof(tos)) == -1)
         {
             char err_buf[512];
             tr_net_strerror(err_buf, sizeof(err_buf), sockerrno);
-            tr_logAddNamedInfo("Net", "Can't set IPv6 QoS '%d': %s", dscp, err_buf);
+            tr_logAddNamedInfo("Net", "Can't set IPv6 QoS '%d': %s", tos, err_buf);
         }
 
 #else
diff --git a/libtransmission/net.h b/libtransmission/net.h
index 66b3449e7..1e4361061 100644
--- a/libtransmission/net.h
+++ b/libtransmission/net.h
@@ -118,6 +118,15 @@ static inline bool tr_address_is_valid(tr_address const* a)
  * Sockets
  **********************************************************************/
 
+/* https://en.wikipedia.org/wiki/Differentiated_services#Class_Selector */
+enum
+{
+    TR_IPTOS_LOWCOST = 0x38, /* AF13: low prio, high drop */
+    TR_IPTOS_LOWDELAY = 0x70, /* AF32: high prio, mid drop */
+    TR_IPTOS_THRUPUT = 0x20, /* CS1: low prio, undef drop */
+    TR_IPTOS_RELIABLE = 0x28 /* AF11: low prio, low drop */
+};
+
 struct tr_session;
 
 struct tr_peer_socket tr_netOpenPeerSocket(tr_session* session, tr_address const* addr, tr_port port, bool clientIsSeed);
diff --git a/libtransmission/session.c b/libtransmission/session.c
index 73e1f2569..94faf446d 100644
--- a/libtransmission/session.c
+++ b/libtransmission/session.c
@@ -265,27 +265,27 @@ static int parse_tos(char const* str)
 
     if (evutil_ascii_strcasecmp(str, "lowcost") == 0)
     {
-        return 0x10;
+        return TR_IPTOS_LOWCOST;
     }
 
     if (evutil_ascii_strcasecmp(str, "mincost") == 0)
     {
-        return 0x10;
+        return TR_IPTOS_LOWCOST;
     }
 
     if (evutil_ascii_strcasecmp(str, "throughput") == 0)
     {
-        return 0x08;
+        return TR_IPTOS_THRUPUT;
     }
 
     if (evutil_ascii_strcasecmp(str, "reliability") == 0)
     {
-        return 0x04;
+        return TR_IPTOS_RELIABLE;
     }
 
     if (evutil_ascii_strcasecmp(str, "lowdelay") == 0)
     {
-        return 0x02;
+        return TR_IPTOS_LOWDELAY;
     }
 
     value = strtol(str, &p, 0);
@@ -307,16 +307,16 @@ static char const* format_tos(int value)
     case 0:
         return "default";
 
-    case 0x10:
+    case TR_IPTOS_LOWCOST:
         return "lowcost";
 
-    case 0x08:
+    case TR_IPTOS_THRUPUT:
         return "throughput";
 
-    case 0x04:
+    case TR_IPTOS_RELIABLE:
         return "reliability";
 
-    case 0x02:
+    case TR_IPTOS_LOWDELAY:
         return "lowdelay";
 
     default: