diff --git a/examples/nanocoap_server/coap_handler.c b/examples/nanocoap_server/coap_handler.c
index f777dab9c0e7..e4a1a40d1501 100644
--- a/examples/nanocoap_server/coap_handler.c
+++ b/examples/nanocoap_server/coap_handler.c
@@ -10,14 +10,17 @@
 #include <stdio.h>
 #include <string.h>
 
-#include "event/callback.h"
-#include "event/timeout.h"
-#include "event/thread.h"
 #include "fmt.h"
 #include "net/nanocoap.h"
 #include "net/nanocoap_sock.h"
 #include "hashes/sha256.h"
-#include "kernel_defines.h"
+
+#if MODULE_EVENT_THREAD
+#  include "event.h"
+#  include "event/thread.h"
+#  include "event/timeout.h"
+#  include "event/callback.h"
+#endif
 
 /* internal value that can be read/written via CoAP */
 static uint8_t internal_value = 0;
@@ -158,7 +161,7 @@ ssize_t _sha256_handler(coap_pkt_t* pkt, uint8_t *buf, size_t len, coap_request_
         return reply_len;
     }
 
-    uint8_t *pkt_pos = (uint8_t*)pkt->hdr + reply_len;
+    uint8_t *pkt_pos = pkt->buf + reply_len;
     if (blockwise) {
         pkt_pos += coap_opt_put_block1_control(pkt_pos, 0, &block1);
     }
@@ -167,7 +170,7 @@ ssize_t _sha256_handler(coap_pkt_t* pkt, uint8_t *buf, size_t len, coap_request_
         pkt_pos += fmt_bytes_hex((char *)pkt_pos, digest, sizeof(digest));
     }
 
-    return pkt_pos - (uint8_t*)pkt->hdr;
+    return pkt_pos - pkt->buf;
 }
 
 NANOCOAP_RESOURCE(echo) {
diff --git a/tests/net/nanocoap_cli/nanocli_client.c b/tests/net/nanocoap_cli/nanocli_client.c
index 3266c69055d0..a64d1369b867 100644
--- a/tests/net/nanocoap_cli/nanocli_client.c
+++ b/tests/net/nanocoap_cli/nanocli_client.c
@@ -25,7 +25,6 @@
 
 #include "net/coap.h"
 #include "net/gnrc/netif.h"
-#include "net/ipv6.h"
 #include "net/nanocoap.h"
 #include "net/nanocoap_sock.h"
 #include "net/sock/udp.h"
@@ -85,8 +84,7 @@ int nanotest_client_cmd(int argc, char **argv)
 {
     /* Ordered like the RFC method code numbers, but off by 1. GET is code 0. */
     const char *method_codes[] = {"get", "post", "put"};
-    unsigned buflen = 128;
-    uint8_t buf[buflen];
+    uint8_t buf[128];
     coap_pkt_t pkt;
     size_t len;
     uint8_t token[2] = {0xDA, 0xEC};
@@ -106,13 +104,13 @@ int nanotest_client_cmd(int argc, char **argv)
         goto end;
     }
 
-    pkt.hdr = (coap_hdr_t *)buf;
+    pkt.buf = buf;
 
     /* parse options */
     if (argc == 5 || argc == 6) {
-        ssize_t hdrlen = coap_build_hdr(pkt.hdr, COAP_TYPE_CON, &token[0], 2,
+        ssize_t hdrlen = coap_build_udp_hdr(buf, sizeof(buf), COAP_TYPE_CON, &token[0], 2,
                                         code_pos+1, 1);
-        coap_pkt_init(&pkt, &buf[0], buflen, hdrlen);
+        coap_pkt_init(&pkt, &buf[0], sizeof(buf), hdrlen);
         coap_opt_add_string(&pkt, COAP_OPT_URI_PATH, argv[4], '/');
         if (argc == 6) {
             coap_opt_add_uint(&pkt, COAP_OPT_CONTENT_FORMAT, COAP_FORMAT_TEXT);
@@ -129,7 +127,7 @@ int nanotest_client_cmd(int argc, char **argv)
         printf("nanocli: sending msg ID %u, %" PRIuSIZE " bytes\n", coap_get_id(&pkt),
                len);
 
-        ssize_t res = _send(&pkt, buflen, argv[2], argv[3]);
+        ssize_t res = _send(&pkt, sizeof(buf), argv[2], argv[3]);
         if (res < 0) {
             printf("nanocli: msg send failed: %" PRIdSIZE "\n", res);
         }
diff --git a/tests/pkg/edhoc_c/initiator.c b/tests/pkg/edhoc_c/initiator.c
index c0597ef3751f..9e8301a7eb8e 100644
--- a/tests/pkg/edhoc_c/initiator.c
+++ b/tests/pkg/edhoc_c/initiator.c
@@ -20,9 +20,7 @@
 #include <stdio.h>
 
 #include "net/gnrc/netif.h"
-#include "net/ipv6.h"
 #include "net/nanocoap_sock.h"
-#include "shell.h"
 
 #include "edhoc/edhoc.h"
 #include "edhoc_keys.h"
@@ -33,9 +31,6 @@
 #include "tinycrypt/sha256.h"
 #endif
 
-#define ENABLE_DEBUG        0
-#include "debug.h"
-
 #define COAP_BUF_SIZE     (256U)
 
 #if IS_ACTIVE(CONFIG_INITIATOR)
@@ -114,11 +109,9 @@ static ssize_t _build_coap_pkt(coap_pkt_t *pkt, uint8_t *buf, ssize_t buflen,
     uint8_t token[2] = { 0xDA, 0xEC };
     ssize_t len = 0;
 
-    /* set pkt buffer */
-    pkt->hdr = (coap_hdr_t *)buf;
     /* build header, confirmed message always post */
-    ssize_t hdrlen = coap_build_hdr(pkt->hdr, COAP_TYPE_CON, token,
-                                    sizeof(token), COAP_METHOD_POST, 1);
+    ssize_t hdrlen = coap_build_udp_hdr(buf, buflen, COAP_TYPE_CON, token,
+                                        sizeof(token), COAP_METHOD_POST, 1);
 
     coap_pkt_init(pkt, buf, buflen, hdrlen);
     coap_opt_add_string(pkt, COAP_OPT_URI_PATH, "/.well-known/edhoc", '/');
diff --git a/tests/riotboot_flashwrite/coap_handler.c b/tests/riotboot_flashwrite/coap_handler.c
index 12a09de83916..e721ffa87c6c 100644
--- a/tests/riotboot_flashwrite/coap_handler.c
+++ b/tests/riotboot_flashwrite/coap_handler.c
@@ -8,7 +8,6 @@
 
 #include <stdlib.h>
 #include <stdio.h>
-#include <string.h>
 
 #include "net/nanocoap.h"
 #include "riotboot/flashwrite.h"
@@ -72,10 +71,10 @@ ssize_t _flashwrite_handler(coap_pkt_t* pkt, uint8_t *buf, size_t len, coap_requ
         return reply_len;
     }
 
-    uint8_t *pkt_pos = (uint8_t*)pkt->hdr + reply_len;
+    uint8_t *pkt_pos = pkt->buf + reply_len;
     pkt_pos += coap_put_block1_ok(pkt_pos, &block1, 0);
 
-    return pkt_pos - (uint8_t*)pkt->hdr;
+    return pkt_pos - pkt->buf;
 }
 
 NANOCOAP_RESOURCE(flashwrite) {