diff --git a/include/openvpn-msg.h b/include/openvpn-msg.h
index a0cec53..34f50c8 100644
--- a/include/openvpn-msg.h
+++ b/include/openvpn-msg.h
@@ -66,7 +66,8 @@
 
 typedef struct
 {
-    int index;
+#define TUN_ADAPTER_INDEX_INVALID ((DWORD)-1)
+    DWORD index;
     char name[256];
 } interface_t;
 
diff --git a/src/openvpn/dns.c b/src/openvpn/dns.c
index 4a4bb0c..a42d032 100644
--- a/src/openvpn/dns.c
+++ b/src/openvpn/dns.c
@@ -468,9 +468,10 @@
     make_domain_list("dns search domains", search_domains, false, nrpt.search_domains,
                      sizeof(nrpt.search_domains));
 
-    msg(D_LOW, "%s NRPT DNS%s%s on '%s' (if_index = %d) using service",
+    msg(D_LOW, "%s NRPT DNS%s%s on '%s' (if_index = %lu) using service",
         (add ? "Setting" : "Deleting"), nrpt.resolve_domains[0] != 0 ? ", resolve domains" : "",
-        nrpt.search_domains[0] != 0 ? ", search domains" : "", nrpt.iface.name, nrpt.iface.index);
+        nrpt.search_domains[0] != 0 ? ", search domains" : "",
+        nrpt.iface.name, nrpt.iface.index);
 
     send_msg_iservice(o->msg_channel, &nrpt, sizeof(nrpt), &ack, "DNS");
 }
diff --git a/src/openvpn/route.c b/src/openvpn/route.c
index b196713..1cfbf80 100644
--- a/src/openvpn/route.c
+++ b/src/openvpn/route.c
@@ -2389,8 +2389,8 @@
         status = GetIpForwardTable(rt, &size, TRUE);
         if (status != NO_ERROR)
         {
-            msg(D_ROUTE, "NOTE: GetIpForwardTable returned error: %s (code=%u)",
-                strerror_win32(status, gc), (unsigned int)status);
+            msg(D_ROUTE, "NOTE: GetIpForwardTable returned error: %s (code=%lu)",
+                strerror_win32(status, gc), status);
             rt = NULL;
         }
     }
@@ -2470,8 +2470,8 @@
         }
     }
 
-    msg(D_ROUTE, "TEST ROUTES: %d/%d succeeded len=%d ret=%d a=%d u/d=%s", good, count, len,
-        (int)ret, ambig, adapter_up ? "up" : "down");
+    msg(D_ROUTE, "TEST ROUTES: %d/%d succeeded len=%d ret=%u a=%d u/d=%s",
+        good, count, len, ret, ambig, adapter_up ? "up" : "down");
 
     gc_free(&gc);
     return ret;
@@ -2495,9 +2495,9 @@
             const DWORD index = row->dwForwardIfIndex;
             const DWORD metric = row->dwForwardMetric1;
 
-            dmsg(D_ROUTE_DEBUG, "GDGR: route[%lu] %s/%s i=%d m=%d", i,
+            dmsg(D_ROUTE_DEBUG, "GDGR: route[%lu] %s/%s i=%lu m=%lu", i,
                  print_in_addr_t((in_addr_t)net, 0, &gc), print_in_addr_t((in_addr_t)mask, 0, &gc),
-                 (int)index, (int)metric);
+                 index, metric);
 
             if (!net && !mask && metric < lowest_metric)
             {
@@ -2508,7 +2508,7 @@
         }
     }
 
-    dmsg(D_ROUTE_DEBUG, "GDGR: best=%d lm=%u", best, (unsigned int)lowest_metric);
+    dmsg(D_ROUTE_DEBUG, "GDGR: best=%d lm=%lu", best, lowest_metric);
 
     gc_free(&gc);
     return ret;
@@ -2537,12 +2537,12 @@
     status = GetBestInterfaceEx((struct sockaddr *)dest, &best_if_index);
     if (status != NO_ERROR)
     {
-        msg(D_ROUTE, "NOTE: GetBestInterfaceEx returned error: %s (code=%u)",
-            strerror_win32(status, gc), (unsigned int)status);
+        msg(D_ROUTE, "NOTE: GetBestInterfaceEx returned error: %s (code=%lu)",
+            strerror_win32(status, gc), status);
         goto done;
     }
 
-    msg(D_ROUTE_DEBUG, "GetBestInterfaceEx() returned if=%d", (int)best_if_index);
+    msg(D_ROUTE_DEBUG, "GetBestInterfaceEx() returned if=%lu", best_if_index);
 
     /* get the routing information (such as NextHop) for the destination and interface */
     NET_LUID luid;
@@ -2552,8 +2552,8 @@
     status = GetBestRoute2(&luid, best_if_index, NULL, dest, 0, best_route, &best_src);
     if (status != NO_ERROR)
     {
-        msg(D_ROUTE, "NOTE: GetIpForwardEntry2 returned error: %s (code=%u)",
-            strerror_win32(status, gc), (unsigned int)status);
+        msg(D_ROUTE, "NOTE: GetIpForwardEntry2 returned error: %s (code=%lu)",
+            strerror_win32(status, gc), status);
         goto done;
     }
 
@@ -2647,15 +2647,14 @@
             print_in_addr_t(r->gateway, 0, &gc), count);
     }
 
-    dmsg(D_ROUTE_DEBUG, "DEBUG: route find if: on_tun=%d count=%d index=%d", on_tun, count,
-         (int)ret);
+    dmsg(D_ROUTE_DEBUG, "DEBUG: route find if: on_tun=%d count=%d index=%lu",
+         on_tun, count, ret);
 
     gc_free(&gc);
     return ret;
 }
 
 /* IPv6 implementation using GetBestRoute2()
- *   (TBD: dynamic linking so the binary can still run on XP?)
  * https://msdn.microsoft.com/en-us/library/windows/desktop/aa365922(v=vs.85).aspx
  * https://msdn.microsoft.com/en-us/library/windows/desktop/aa814411(v=vs.85).aspx
  */
@@ -2687,8 +2686,8 @@
         print_in6_addr(BestRoute.DestinationPrefix.Prefix.Ipv6.sin6_addr, 0, &gc),
         BestRoute.DestinationPrefix.PrefixLength,
         print_in6_addr(BestRoute.NextHop.Ipv6.sin6_addr, 0, &gc));
-    msg(D_ROUTE, "GDG6: Metric=%d, Loopback=%d, AA=%d, I=%d", (int)BestRoute.Metric,
-        (int)BestRoute.Loopback, (int)BestRoute.AutoconfigureAddress, (int)BestRoute.Immortal);
+    msg(D_ROUTE, "GDG6: Metric=%lu, Loopback=%u, AA=%u, I=%u", BestRoute.Metric,
+        BestRoute.Loopback, BestRoute.AutoconfigureAddress, BestRoute.Immortal);
 
     rgi6->gateway.addr_ipv6 = BestRoute.NextHop.Ipv6.sin6_addr;
     rgi6->adapter_index = BestRoute.InterfaceIndex;
@@ -2753,8 +2752,8 @@
         else
         {
             /* failed, try increasing the metric to work around Vista issue */
-            const unsigned int forward_metric_limit =
-                2048; /* iteratively retry higher metrics up to this limit */
+            /* iteratively retry higher metrics up to this limit */
+            const DWORD forward_metric_limit = 2048;
 
             for (; fr.dwForwardMetric1 <= forward_metric_limit; ++fr.dwForwardMetric1)
             {
@@ -2767,8 +2766,8 @@
                     if (status == NO_ERROR)
                     {
                         msg(D_ROUTE,
-                            "ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=%u and dwForwardType=%u",
-                            (unsigned int)fr.dwForwardMetric1, (unsigned int)fr.dwForwardType);
+                            "ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=%lu and dwForwardType=%lu",
+                            fr.dwForwardMetric1, fr.dwForwardType);
                         ret = RTA_SUCCESS;
                         goto doublebreak;
                     }
@@ -2790,8 +2789,8 @@
                 {
                     msg(M_WARN,
                         "ERROR: route addition failed using CreateIpForwardEntry: "
-                        "%s [status=%u if_index=%u]",
-                        strerror_win32(status, &gc), (unsigned int)status, (unsigned int)if_index);
+                        "%s [status=%lu if_index=%lu]",
+                        strerror_win32(status, &gc), status, if_index);
                 }
             }
         }
@@ -2855,7 +2854,7 @@
         ret = (ack.error_number == ERROR_OBJECT_ALREADY_EXISTS) ? RTA_EEXIST : RTA_ERROR;
         if (ret == RTA_ERROR)
         {
-            msg(M_WARN, "ERROR: route %s failed using service: %s [status=%u if_index=%d]",
+            msg(M_WARN, "ERROR: route %s failed using service: %s [status=%u if_index=%lu]",
                 (add ? "addition" : "deletion"), strerror_win32(ack.error_number, &gc),
                 ack.error_number, rt->iface.index);
         }
@@ -2869,17 +2868,12 @@
     return ret;
 }
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wsign-compare"
-#endif
-
 /* Returns RTA_SUCCESS on success, RTA_EEXIST if route exists, RTA_ERROR on error */
 static int
 do_route_ipv4_service(const bool add, const struct route_ipv4 *r, const struct tuntap *tt)
 {
     DWORD if_index = windows_route_find_if_index(r, tt);
-    if (if_index == ~0)
+    if (if_index == TUN_ADAPTER_INDEX_INVALID)
     {
         return RTA_ERROR;
     }
@@ -3023,10 +3017,6 @@
     return status;
 }
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
-
 /* Returns RTA_SUCCESS on success, RTA_EEXIST if route exists, RTA_ERROR on error */
 static int
 add_route_service(const struct route_ipv4 *r, const struct tuntap *tt)
@@ -3057,14 +3047,14 @@
 format_route_entry(const MIB_IPFORWARDROW *r, struct gc_arena *gc)
 {
     struct buffer out = alloc_buf_gc(256, gc);
-    buf_printf(&out, "%s %s %s p=%d i=%d t=%d pr=%d a=%d h=%d m=%d/%d/%d/%d/%d",
+    buf_printf(&out, "%s %s %s p=%lu i=%lu t=%lu pr=%lu a=%lu h=%lu m=%lu/%lu/%lu/%lu/%lu",
                print_in_addr_t(r->dwForwardDest, IA_NET_ORDER, gc),
                print_in_addr_t(r->dwForwardMask, IA_NET_ORDER, gc),
-               print_in_addr_t(r->dwForwardNextHop, IA_NET_ORDER, gc), (int)r->dwForwardPolicy,
-               (int)r->dwForwardIfIndex, (int)r->dwForwardType, (int)r->dwForwardProto,
-               (int)r->dwForwardAge, (int)r->dwForwardNextHopAS, (int)r->dwForwardMetric1,
-               (int)r->dwForwardMetric2, (int)r->dwForwardMetric3, (int)r->dwForwardMetric4,
-               (int)r->dwForwardMetric5);
+               print_in_addr_t(r->dwForwardNextHop, IA_NET_ORDER, gc), r->dwForwardPolicy,
+               r->dwForwardIfIndex, r->dwForwardType, r->dwForwardProto,
+               r->dwForwardAge, r->dwForwardNextHopAS, r->dwForwardMetric1,
+               r->dwForwardMetric2, r->dwForwardMetric3, r->dwForwardMetric4,
+               r->dwForwardMetric5);
     return BSTR(&out);
 }
 
diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 7f96602..64e3b45 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -158,7 +158,7 @@
 
     if (ack.error_number != NO_ERROR)
     {
-        msg(M_WARN, "TUN: %s address failed using service: %s [status=%u if_index=%d]",
+        msg(M_WARN, "TUN: %s address failed using service: %s [status=%u if_index=%lu]",
             (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc), ack.error_number,
             addr.iface.index);
         goto out;
@@ -220,7 +220,7 @@
         strncpy(dns.domains + dstlen, o->domain_search_list[i], srclen + 1);
     }
 
-    msg(D_LOW, "%s DNS domains on '%s' (if_index = %d) using service",
+    msg(D_LOW, "%s DNS domains on '%s' (if_index = %lu) using service",
         (add ? "Setting" : "Deleting"), dns.iface.name, dns.iface.index);
     if (!send_msg_iservice(o->msg_channel, &dns, sizeof(dns), &ack, "TUN"))
     {
@@ -289,7 +289,7 @@
         }
     }
 
-    msg(D_LOW, "%s %s dns servers on '%s' (if_index = %d) using service",
+    msg(D_LOW, "%s %s dns servers on '%s' (if_index = %lu) using service",
         (add ? "Setting" : "Deleting"), ip_proto_name, dns.iface.name, dns.iface.index);
 
     if (!send_msg_iservice(pipe, &dns, sizeof(dns), &ack, "TUN"))
@@ -346,7 +346,7 @@
         wins.addr[i].ipv4.s_addr = htonl(tt->options.wins[i]);
     }
 
-    msg(D_LOW, "%s WINS servers on '%s' (if_index = %d) using service",
+    msg(D_LOW, "%s WINS servers on '%s' (if_index = %lu) using service",
         (add ? "Setting" : "Deleting"), wins.iface.name, wins.iface.index);
 
     if (!send_msg_iservice(pipe, &wins, sizeof(wins), &ack, "TUN"))
@@ -357,8 +357,8 @@
     if (ack.error_number != NO_ERROR)
     {
         msg(M_WARN, "TUN: %s WINS failed using service: %s [status=%u if_name=%s]",
-            (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc), ack.error_number,
-            wins.iface.name);
+            (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc),
+            ack.error_number, wins.iface.name);
         goto out;
     }
 
@@ -398,13 +398,13 @@
 
     if (ack.error_number != NO_ERROR)
     {
-        msg(M_NONFATAL, "TUN: setting %s mtu using service failed: %s [status=%u if_index=%d]",
+        msg(M_NONFATAL, "TUN: setting %s mtu using service failed: %s [status=%u if_index=%lu]",
             family_name, strerror_win32(ack.error_number, &gc), ack.error_number,
             mtu_msg.iface.index);
     }
     else
     {
-        msg(M_INFO, "%s MTU set to %d on interface %d using service", family_name, mtu,
+        msg(M_INFO, "%s MTU set to %d on interface %lu using service", family_name, mtu,
             mtu_msg.iface.index);
         ret = true;
     }
@@ -3428,7 +3428,7 @@
     if (dev_info_set == INVALID_HANDLE_VALUE)
     {
         err = GetLastError();
-        msg(M_FATAL, "Error [%u] opening device information set key: %s", (unsigned int)err,
+        msg(M_FATAL, "Error [%lu] opening device information set key: %s", err,
             strerror_win32(err, gc));
     }
 
@@ -4111,7 +4111,7 @@
 
     if ((status = GetAdaptersInfo(NULL, &size)) != ERROR_BUFFER_OVERFLOW)
     {
-        msg(M_INFO, "GetAdaptersInfo #1 failed (status=%u) : %s", (unsigned int)status,
+        msg(M_INFO, "GetAdaptersInfo #1 failed (status=%lu) : %s", status,
             strerror_win32(status, gc));
     }
     else
@@ -4119,7 +4119,7 @@
         pi = (PIP_ADAPTER_INFO)gc_malloc(size, false, gc);
         if ((status = GetAdaptersInfo(pi, &size)) != NO_ERROR)
         {
-            msg(M_INFO, "GetAdaptersInfo #2 failed (status=%u) : %s", (unsigned int)status,
+            msg(M_INFO, "GetAdaptersInfo #2 failed (status=%lu) : %s", status,
                 strerror_win32(status, gc));
             pi = NULL;
         }
@@ -4138,19 +4138,19 @@
     {
         if ((status = GetPerAdapterInfo(index, NULL, &size)) != ERROR_BUFFER_OVERFLOW)
         {
-            msg(M_INFO, "GetPerAdapterInfo #1 failed (status=%u) : %s", (unsigned int)status,
+            msg(M_INFO, "GetPerAdapterInfo #1 failed (status=%lu) : %s", status,
                 strerror_win32(status, gc));
         }
         else
         {
             pi = (PIP_PER_ADAPTER_INFO)gc_malloc(size, false, gc);
-            if ((status = GetPerAdapterInfo((ULONG)index, pi, &size)) == ERROR_SUCCESS)
+            if ((status = GetPerAdapterInfo(index, pi, &size)) == ERROR_SUCCESS)
             {
                 return pi;
             }
             else
             {
-                msg(M_INFO, "GetPerAdapterInfo #2 failed (status=%u) : %s", (unsigned int)status,
+                msg(M_INFO, "GetPerAdapterInfo #2 failed (status=%lu) : %s", status,
                     strerror_win32(status, gc));
             }
         }
@@ -4167,7 +4167,7 @@
 
     if ((status = GetInterfaceInfo(NULL, &size)) != ERROR_INSUFFICIENT_BUFFER)
     {
-        msg(M_INFO, "GetInterfaceInfo #1 failed (status=%u) : %s", (unsigned int)status,
+        msg(M_INFO, "GetInterfaceInfo #1 failed (status=%lu) : %s", status,
             strerror_win32(status, gc));
     }
     else
@@ -4179,7 +4179,7 @@
         }
         else
         {
-            msg(M_INFO, "GetInterfaceInfo #2 failed (status=%u) : %s", (unsigned int)status,
+            msg(M_INFO, "GetInterfaceInfo #2 failed (status=%lu) : %s", status,
                 strerror_win32(status, gc));
         }
     }
@@ -4456,8 +4456,8 @@
         list = list->Next;
     }
 
-    dmsg(D_ROUTE_DEBUG, "DEBUG: IP Locate: ip=%s nm=%s index=%d count=%d metric=%d",
-         print_in_addr_t(ip, 0, &gc), print_in_addr_t(highest_netmask, 0, &gc), (int)ret,
+    dmsg(D_ROUTE_DEBUG, "DEBUG: IP Locate: ip=%s nm=%s index=%lu count=%d metric=%d",
+         print_in_addr_t(ip, 0, &gc), print_in_addr_t(highest_netmask, 0, &gc), ret,
          count ? *count : -1, lowest_metric);
 
     if (ret == TUN_ADAPTER_INDEX_INVALID && count)
@@ -4526,7 +4526,7 @@
             DWORD status;
             const DWORD context = ip->Context;
 
-            if ((status = DeleteIPAddress((ULONG)context)) == NO_ERROR)
+            if ((status = DeleteIPAddress(context)) == NO_ERROR)
             {
                 msg(M_INFO, "Successfully deleted previously set dynamic IP/netmask: %s/%s",
                     ip->IpAddress.String, ip->IpMask.String);
@@ -4537,8 +4537,8 @@
                 if (strcmp(ip->IpAddress.String, empty) || strcmp(ip->IpMask.String, empty))
                 {
                     msg(M_INFO,
-                        "NOTE: could not delete previously set dynamic IP/netmask: %s/%s (status=%u)",
-                        ip->IpAddress.String, ip->IpMask.String, (unsigned int)status);
+                        "NOTE: could not delete previously set dynamic IP/netmask: %s/%s (status=%lu)",
+                        ip->IpAddress.String, ip->IpMask.String, status);
                 }
             }
             ip = ip->Next;
@@ -4634,7 +4634,7 @@
 show_adapter(msglvl_t msglevel, const IP_ADAPTER_INFO *a, struct gc_arena *gc)
 {
     msg(msglevel, "%s", a->Description);
-    msg(msglevel, "  Index = %d", (int)a->Index);
+    msg(msglevel, "  Index = %lu", a->Index);
     msg(msglevel, "  GUID = %s", a->AdapterName);
     msg(msglevel, "  IP = %s", format_ip_addr_string(&a->IpAddressList, gc));
     msg(msglevel, "  MAC = %s", format_hex_ex(a->Address, a->AddressLength, 0, 1, ":", gc));
@@ -4810,8 +4810,8 @@
         else
         {
             msg(M_WARN,
-                "NOTE: Release of DHCP-assigned IP address lease on TAP-Windows adapter failed: %s (code=%u)",
-                strerror_win32(status, &gc), (unsigned int)status);
+                "NOTE: Release of DHCP-assigned IP address lease on TAP-Windows adapter failed: %s (code=%lu)",
+                strerror_win32(status, &gc), status);
         }
     }
 
@@ -4851,8 +4851,8 @@
         else
         {
             msg(M_WARN,
-                "WARNING: Failed to renew DHCP IP address lease on TAP-Windows adapter: %s (code=%u)",
-                strerror_win32(status, &gc), (unsigned int)status);
+                "WARNING: Failed to renew DHCP IP address lease on TAP-Windows adapter: %s (code=%lu)",
+                strerror_win32(status, &gc), status);
         }
     }
     gc_free(&gc);
@@ -5215,12 +5215,12 @@
 
     if (ack.error_number != NO_ERROR)
     {
-        msg(M_NONFATAL, "TUN: enabling dhcp using service failed: %s [status=%u if_index=%d]",
+        msg(M_NONFATAL, "TUN: enabling dhcp using service failed: %s [status=%u if_index=%lu]",
             strerror_win32(ack.error_number, &gc), ack.error_number, dhcp.iface.index);
     }
     else
     {
-        msg(M_INFO, "DHCP enabled on interface %d using service", dhcp.iface.index);
+        msg(M_INFO, "DHCP enabled on interface %lu using service", dhcp.iface.index);
         ret = true;
     }
 
@@ -5510,7 +5510,7 @@
     /* flush arp cache */
     if (tt->backend_driver == WINDOWS_DRIVER_TAP_WINDOWS6 && index != TUN_ADAPTER_INDEX_INVALID)
     {
-        DWORD status = -1;
+        DWORD status = (DWORD)-1;
 
         if (tt->options.msg_channel)
         {
@@ -5534,7 +5534,7 @@
         {
             msg(M_INFO, "Successful ARP Flush on interface [%lu] %s", index, device_guid);
         }
-        else if (status != -1)
+        else if (status != (DWORD)-1)
         {
             msg(D_TUNTAP_INFO,
                 "NOTE: FlushIpNetTable failed on interface [%lu] %s (status=%lu) : %s", index,
@@ -6232,11 +6232,12 @@
     if (tt->ipapi_context_defined)
     {
         DWORD status;
+
         if ((status = DeleteIPAddress(tt->ipapi_context)) != NO_ERROR)
         {
             msg(M_WARN,
-                "Warning: DeleteIPAddress[%u] failed on TAP-Windows adapter, status=%u : %s",
-                (unsigned int)tt->ipapi_context, (unsigned int)status, strerror_win32(status, &gc));
+                "Warning: DeleteIPAddress[%lu] failed on TAP-Windows adapter, status=%lu : %s",
+                tt->ipapi_context, status, strerror_win32(status, &gc));
         }
     }
 
diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
index 4d6dfbb..ecb5e88 100644
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -61,8 +61,6 @@
 
 #if defined(_WIN32) || defined(TARGET_ANDROID) || defined(DHCP_UNIT_TEST)
 
-#define TUN_ADAPTER_INDEX_INVALID ((DWORD)-1)
-
 /* time constants for --ip-win32 adaptive */
 #define IPW32_SET_ADAPTIVE_DELAY_WINDOW 300
 #define IPW32_SET_ADAPTIVE_TRY_NETSH    20
@@ -230,7 +228,7 @@
     in_addr_t adapter_netmask;
 
     /* Windows adapter index for TAP-Windows adapter,
-     * ~0 if undefined */
+     * TUN_ADAPTER_INDEX_INVALID if undefined */
     DWORD adapter_index;
 
     int standby_iter;
diff --git a/src/openvpn/win32.c b/src/openvpn/win32.c
index ac449fd..b2a7331 100644
--- a/src/openvpn/win32.c
+++ b/src/openvpn/win32.c
@@ -1185,7 +1185,7 @@
     if (ack.error_number != NO_ERROR)
     {
         msg(M_WARN,
-            "WFP block: %s block filters using service failed: %s [status=0x%x if_index=%d]",
+            "WFP block: %s block filters using service failed: %s [status=0x%x if_index=%lu]",
             (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc), ack.error_number,
             data.iface.index);
         goto out;
diff --git a/src/openvpnserv/interactive.c b/src/openvpnserv/interactive.c
index 09c709e..b50aeb3 100644
--- a/src/openvpnserv/interactive.c
+++ b/src/openvpnserv/interactive.c
@@ -96,7 +96,7 @@
 typedef struct
 {
     HANDLE engine;
-    int index;
+    DWORD index;
     int metric_v4;
     int metric_v6;
 } wfp_block_data_t;
@@ -584,7 +584,7 @@
     addr_row->Address = sockaddr_inet(msg->family, &msg->address);
     addr_row->OnLinkPrefixLength = (UINT8)msg->prefix_len;
 
-    if (msg->iface.index != -1)
+    if (msg->iface.index != TUN_ADAPTER_INDEX_INVALID)
     {
         addr_row->InterfaceIndex = msg->iface.index;
     }
@@ -667,7 +667,7 @@
     fwd_row->DestinationPrefix.PrefixLength = (UINT8)msg->prefix_len;
     fwd_row->NextHop = sockaddr_inet(msg->family, &msg->gateway);
 
-    if (msg->iface.index != -1)
+    if (msg->iface.index != TUN_ADAPTER_INDEX_INVALID)
     {
         fwd_row->InterfaceIndex = msg->iface.index;
     }
@@ -1010,7 +1010,7 @@
  * if action = "set" then "static" is added before $addr
  */
 static DWORD
-netsh_wins_cmd(const wchar_t *action, int if_index, const wchar_t *addr)
+netsh_wins_cmd(const wchar_t *action, DWORD if_index, const wchar_t *addr)
 {
     DWORD err = 0;
     int timeout = 30000; /* in msec */
@@ -1036,7 +1036,7 @@
     /* cmd template:
      * netsh interface ip $action wins $if_name $static $addr
      */
-    const wchar_t *fmt = L"netsh interface ip %ls wins %d %ls %ls";
+    const wchar_t *fmt = L"netsh interface ip %ls wins %lu %ls %ls";
 
     /* max cmdline length in wchars -- include room for worst case and some */
     size_t ncmdline = wcslen(fmt) + 11 /*if_index*/ + wcslen(action) + wcslen(addr)
@@ -2984,7 +2984,7 @@
          */
     }
 
-    int *if_index = malloc(sizeof(msg->iface.index));
+    PDWORD if_index = malloc(sizeof(msg->iface.index));
     if (if_index)
     {
         *if_index = msg->iface.index;
@@ -3017,7 +3017,7 @@
     /* cmd template:
      * netsh interface ipv4 set address name=$if_index source=dhcp
      */
-    const wchar_t *fmt = L"netsh interface ipv4 set address name=\"%d\" source=dhcp";
+    const wchar_t *fmt = L"netsh interface ipv4 set address name=\"%lu\" source=dhcp";
 
     /* max cmdline length in wchars -- include room for if index:
      * 10 chars for 32 bit int in decimal and +1 for NUL
@@ -3250,7 +3250,7 @@
                     break;
 
                 case undo_wins:
-                    netsh_wins_cmd(L"delete", *(int *)item->data, NULL);
+                    netsh_wins_cmd(L"delete", *(PDWORD)item->data, NULL);
                     break;
 
                 case wfp_block: