diff --git a/sys/net/application_layer/dhcpv6/client.c b/sys/net/application_layer/dhcpv6/client.c
index 0e92501e36..319e843e7e 100644
--- a/sys/net/application_layer/dhcpv6/client.c
+++ b/sys/net/application_layer/dhcpv6/client.c
@@ -839,7 +839,7 @@ static void _request_renew_rebind(uint8_t type)
         case DHCPV6_RENEW:
             irt = DHCPV6_REN_TIMEOUT;
             mrt = DHCPV6_REN_MAX_RT;
-            mrd = rebind_time - t2;
+            mrd = rebind_time - _now_sec();
             break;
         case DHCPV6_REBIND: {
             irt = DHCPV6_REB_TIMEOUT;
@@ -858,7 +858,7 @@ static void _request_renew_rebind(uint8_t type)
                     mrd = valid_until;
                 }
             }
-            if (mrd > 0) {
+            if (mrd == 0) {
                 /* all leases already expired, don't try to rebind and
                  * solicit immediately */
                 _post_solicit_servers();
diff --git a/sys/net/gnrc/application_layer/dhcpv6/client.c b/sys/net/gnrc/application_layer/dhcpv6/client.c
index 2c95e3277c..0139ea623a 100644
--- a/sys/net/gnrc/application_layer/dhcpv6/client.c
+++ b/sys/net/gnrc/application_layer/dhcpv6/client.c
@@ -25,6 +25,7 @@
 #include "net/gnrc/rpl.h"
 #include "net/sock.h"
 #include "timex.h"
+#include "evtimer.h"
 
 #include "net/dhcpv6/client.h"
 
@@ -183,13 +184,14 @@ uint32_t dhcpv6_client_prefix_valid_until(unsigned netif,
     gnrc_ipv6_nib_pl_t ple;
     void *state = NULL;
     uint32_t max_valid = 0;
+    uint32_t now = evtimer_now_msec();
 
     while (gnrc_ipv6_nib_pl_iter(netif, &state, &ple)) {
         if ((ple.pfx_len == pfx_len) &&
-            ((ple.valid_until / MS_PER_SEC) > max_valid) &&
+            (((ple.valid_until - now) / MS_PER_SEC) > max_valid) &&
             (ipv6_addr_match_prefix(&ple.pfx,
                                     pfx) >= ple.pfx_len)) {
-            max_valid = ple.valid_until / MS_PER_SEC;
+            max_valid = (ple.valid_until - now) / MS_PER_SEC;
         }
     }
     return max_valid;