diff --git a/CHANGELOG b/CHANGELOG
index ee04d033..b3f6890f 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -80,6 +80,10 @@ HISTORY
 
  ++ Bugfixes:
 
+  2012-08-13: Simon Goldschmidt
+  * dhcp.c: fixed bug #36645: Calling dhcp_release before dhcp_start
+    dereferences NULL
+
   2012-08-13: Simon Goldschmidt
   * msg_out.c: fixed bug #36840 snmp_send_trap() NULL de-reference if traps
     configured but no interfaces available
diff --git a/src/core/dhcp.c b/src/core/dhcp.c
index 2851d712..f0f594f1 100644
--- a/src/core/dhcp.c
+++ b/src/core/dhcp.c
@@ -1164,6 +1164,9 @@ dhcp_release(struct netif *netif)
   err_t result;
   u16_t msecs;
   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_release()\n"));
+  if (dhcp == NULL) {
+    return ERR_ARG;
+  }
 
   /* idle DHCP client */
   dhcp_set_state(dhcp, DHCP_OFF);