diff --git a/CHANGELOG b/CHANGELOG
index 2b144a65..5a15ef79 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -245,6 +245,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2015-05-19: Simon Goldschmidt
+  * dhcp.h/.c: fixed bugs #45140 and #45141 (dhcp was not stopped correctly after
+    fixing bug #38204)
+
   2015-03-21: Simon Goldschmidt (patch by Homyak)
   * tcp_in.c: fixed bug #44766 (LWIP_WND_SCALE: tcphdr->wnd was not scaled in
     two places)
diff --git a/src/core/dhcp.c b/src/core/dhcp.c
index e9275264..26195682 100644
--- a/src/core/dhcp.c
+++ b/src/core/dhcp.c
@@ -356,20 +356,21 @@ dhcp_coarse_tmr(void)
   /* iterate through all network interfaces */
   while (netif != NULL) {
     /* only act on DHCP configured interfaces */
-    if (netif->dhcp != NULL) {
+    struct dhcp* dhcp = netif->dhcp;
+    if ((dhcp != NULL) && (dhcp->state != DHCP_STATE_OFF)) {
       /* compare lease time to expire timeout */
-      if (++netif->dhcp->lease_used == netif->dhcp->t0_timeout) {
+      if (dhcp->t0_timeout && (++dhcp->lease_used == dhcp->t0_timeout)) {
         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_coarse_tmr(): t0 timeout\n"));
         /* this clients' lease time has expired */
         dhcp_release(netif);
         dhcp_discover(netif);
       /* timer is active (non zero), and triggers (zeroes) now? */
-      } else if (netif->dhcp->t2_rebind_time-- == 1) {
+      } else if (dhcp->t2_rebind_time && (dhcp->t2_rebind_time-- == 1)) {
         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_coarse_tmr(): t2 timeout\n"));
         /* this clients' rebind timeout triggered */
         dhcp_t2_timeout(netif);
       /* timer is active (non zero), and triggers (zeroes) now */
-      } else if (netif->dhcp->t1_renew_time-- == 1) {
+      } else if (dhcp->t1_renew_time && (dhcp->t1_renew_time-- == 1)) {
         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_coarse_tmr(): t1 timeout\n"));
         /* this clients' renewal timeout triggered */
         dhcp_t1_timeout(netif);
@@ -1204,7 +1205,6 @@ dhcp_release(struct netif *netif)
 {
   struct dhcp *dhcp = netif->dhcp;
   err_t result;
-  u16_t msecs;
   ip_addr_t server_ip_addr;
   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_release()\n"));
   if (dhcp == NULL) {
@@ -1223,7 +1223,13 @@ dhcp_release(struct netif *netif)
   ip4_addr_set_zero(&dhcp->offered_si_addr);
 #endif /* LWIP_DHCP_BOOTP_FILE */
   dhcp->offered_t0_lease = dhcp->offered_t1_renew = dhcp->offered_t2_rebind = 0;
-  
+  dhcp->t1_renew_time = dhcp->t2_rebind_time = dhcp->lease_used = dhcp->t0_timeout = 0;
+
+  if (!dhcp_supplied_address(netif)) {
+    /* don't issue release message when address is not dhcp-assigned */
+    return ERR_OK;
+  }
+
   /* create and initialize the DHCP message header */
   result = dhcp_create_msg(netif, dhcp, DHCP_RELEASE);
   if (result == ERR_OK) {
@@ -1238,14 +1244,9 @@ dhcp_release(struct netif *netif)
     dhcp_delete_msg(dhcp);
     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_release: RELEASED, DHCP_STATE_OFF\n"));
   } else {
+    /* sending release failed, but that's not a problem since the correct behaviour of dhcp does not rely on release */
     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_release: could not allocate DHCP request\n"));
   }
-  if (dhcp->tries < 255) {
-    dhcp->tries++;
-  }
-  msecs = dhcp->tries < 10 ? dhcp->tries * 1000 : 10 * 1000;
-  dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
-  LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_release(): set request timeout %"U16_F" msecs\n", msecs));
   /* remove IP address from interface (prevents routing from selecting this interface) */
   netif_set_addr(netif, IP4_ADDR_ANY, IP4_ADDR_ANY, IP4_ADDR_ANY);