diff --git a/examples/coap-server.c b/examples/coap-server.c
index 57665a65fc..7835d3c367 100644
--- a/examples/coap-server.c
+++ b/examples/coap-server.c
@@ -994,7 +994,7 @@ hnd_proxy_uri(coap_resource_t *resource COAP_UNUSED,
   size_t total;
   coap_binary_t *body_data = NULL;
   const uint8_t *data;
-  coap_pdu_t *pdu;
+  coap_pdu_t *pdu = NULL;
   coap_optlist_t *optlist = NULL;
   coap_opt_t *option;
   coap_bin_const_t token = coap_pdu_get_token(request);
@@ -1093,7 +1093,6 @@ hnd_proxy_uri(coap_resource_t *resource COAP_UNUSED,
     if (!coap_add_token(pdu, token.length, token.s)) {
       coap_log_debug("cannot add token to proxy request\n");
       coap_pdu_set_code(response, COAP_RESPONSE_CODE_INTERNAL_ERROR);
-      coap_delete_pdu(pdu);
       goto cleanup;
     }
 
@@ -1166,6 +1165,7 @@ hnd_proxy_uri(coap_resource_t *resource COAP_UNUSED,
      * Do not update with response code (hence empty ACK) as will be sending
      * separate response when response comes back from upstream server
      */
+    pdu = NULL;
     goto cleanup;
   } else {
     /* TODO http & https */
@@ -1175,6 +1175,7 @@ hnd_proxy_uri(coap_resource_t *resource COAP_UNUSED,
   coap_delete_string(uri_path);
   coap_delete_string(uri_query);
   coap_delete_binary(body_data);
+  coap_delete_pdu(pdu);
 }
 
 #endif /* SERVER_CAN_PROXY */
diff --git a/src/coap_block.c b/src/coap_block.c
index 497cad919f..bc0fc3e7cf 100644
--- a/src/coap_block.c
+++ b/src/coap_block.c
@@ -3675,6 +3675,7 @@ coap_handle_response_get_block(coap_context_t *context,
       STATE_TOKEN_BASE(coap_decode_var_bytes8(rcvd->actual_token.s,
                                               rcvd->actual_token.length));
 
+  coap_lock_check_locked(context);
   memset(&block, 0, sizeof(block));
 #if COAP_Q_BLOCK_SUPPORT
   memset(&qblock, 0, sizeof(qblock));
diff --git a/src/coap_net.c b/src/coap_net.c
index b1323db45e..91f62e78b5 100644
--- a/src/coap_net.c
+++ b/src/coap_net.c
@@ -585,7 +585,7 @@ coap_new_context(const coap_address_t *listen_addr) {
   memset(c, 0, sizeof(coap_context_t));
 
   coap_lock_init(c);
-  coap_lock_lock(c, return NULL);
+  coap_lock_lock(c, coap_free_type(COAP_CONTEXT, c); return NULL);
 #ifdef COAP_EPOLL_SUPPORT
   c->epfd = epoll_create1(0);
   if (c->epfd == -1) {
diff --git a/src/coap_resource.c b/src/coap_resource.c
index ea06d6bfcc..e10cd5a7d0 100644
--- a/src/coap_resource.c
+++ b/src/coap_resource.c
@@ -1075,6 +1075,8 @@ coap_notify_observers(coap_context_t *context, coap_resource_t *r,
   coap_tick_t now;
   coap_session_t *obs_session;
 
+  coap_lock_check_locked(context);
+
   if (r->observable && (r->dirty || r->partiallydirty)) {
     r->partiallydirty = 0;