diff --git a/include/coap2/coap_dtls.h b/include/coap2/coap_dtls.h
index 0aeb8634..fdd8cc82 100644
--- a/include/coap2/coap_dtls.h
+++ b/include/coap2/coap_dtls.h
@@ -185,25 +185,13 @@ typedef coap_dtls_key_t *(*coap_dtls_sni_callback_t)(const char *sni,
              void* arg);
 
 
-#if defined(_MSC_VER)
-typedef enum
-coap_dtls_pki_version_t : unsigned char
-#else /* !_MSC_VER */
-typedef enum
-__attribute__ ((__packed__))
-#endif /* !_MSC_VER */
-{
-  COAP_DTLS_PKI_SETUP_VERSION_V1 = 1,
-  COAP_DTLS_PKI_SETUP_VERSION =
-              COAP_DTLS_PKI_SETUP_VERSION_V1, /**< Latest PKI setup version */
-} coap_dtls_pki_version_t;
+#define COAP_DTLS_PKI_SETUP_VERSION 1 /**< Latest PKI setup version */
 
 /**
  * The structure used for defining the PKI setup data to be used.
  */
 typedef struct coap_dtls_pki_t {
-  coap_dtls_pki_version_t version; /** Set to COAP_DTLS_PKI_SETUP_VERSION to
-                                   support the version of the struct */
+  uint8_t version; /** Set to 1 to support this version of the struct */
 
   /* Options to enable different TLS functionality in libcoap */
   uint8_t verify_peer_cert;        /**< 1 if peer cert is to be verified */
diff --git a/include/coap2/coap_session.h b/include/coap2/coap_session.h
index d8e041de..44dd5c8c 100644
--- a/include/coap2/coap_session.h
+++ b/include/coap2/coap_session.h
@@ -37,33 +37,23 @@ typedef struct coap_fixed_point_t {
 #define COAP_PROTO_NOT_RELIABLE(p) ((p)==COAP_PROTO_UDP || (p)==COAP_PROTO_DTLS)
 #define COAP_PROTO_RELIABLE(p) ((p)==COAP_PROTO_TCP || (p)==COAP_PROTO_TLS)
 
-#if defined(_MSC_VER)
-typedef enum
-coap_session_type_t : unsigned char
-#else /* !_MSC_VER */
-typedef enum
-__attribute__ ((__packed__))
-#endif /* !_MSC_VER */
-{
-  COAP_SESSION_TYPE_CLIENT = 1, /**< client-side */
-  COAP_SESSION_TYPE_SERVER, /**< server-side */
-  COAP_SESSION_TYPE_HELLO, /**< server-side ephemeral session for responding to a client hello */
-} coap_session_type_t;
+typedef uint8_t coap_session_type_t;
+/**
+ * coap_session_type_t values
+ */
+#define COAP_SESSION_TYPE_CLIENT 1  /**< client-side */
+#define COAP_SESSION_TYPE_SERVER 2  /**< server-side */
+#define COAP_SESSION_TYPE_HELLO  3  /**< server-side ephemeral session for responding to a client hello */
 
-#if defined(_MSC_VER)
-typedef enum
-coap_session_state_t : unsigned char
-#else /* !_MSC_VER */
-typedef enum
-__attribute__ ((__packed__))
-#endif /* !_MSC_VER */
-{
-  COAP_SESSION_STATE_NONE = 0,
-  COAP_SESSION_STATE_CONNECTING,
-  COAP_SESSION_STATE_HANDSHAKE,
-  COAP_SESSION_STATE_CSM,
-  COAP_SESSION_STATE_ESTABLISHED,
-} coap_session_state_t;
+typedef uint8_t coap_session_state_t;
+/**
+ * coap_session_state_t values
+ */
+#define COAP_SESSION_STATE_NONE                0
+#define COAP_SESSION_STATE_CONNECTING        1
+#define COAP_SESSION_STATE_HANDSHAKE        2
+#define COAP_SESSION_STATE_CSM                3
+#define COAP_SESSION_STATE_ESTABLISHED        4
 
 typedef struct coap_session_t {
   coap_proto_t proto;               /**< protocol used */
diff --git a/include/coap2/pdu.h b/include/coap2/pdu.h
index aec9f9b2..206e2643 100644
--- a/include/coap2/pdu.h
+++ b/include/coap2/pdu.h
@@ -336,23 +336,15 @@ typedef struct coap_pdu_t {
 coap_pdu_t * coap_pdu_from_pbuf(struct pbuf *pbuf);
 #endif
 
+typedef uint8_t coap_proto_t;
 /**
 * coap_proto_t values
 */
-#if defined(_MSC_VER)
-typedef enum
-coap_proto_t : unsigned char
-#else /* !_MSC_VER */
-typedef enum
-__attribute__ ((__packed__))
-#endif /* !_MSC_VER */
-{
-  COAP_PROTO_NONE = 0,
-  COAP_PROTO_UDP,
-  COAP_PROTO_DTLS,
-  COAP_PROTO_TCP,
-  COAP_PROTO_TLS,
-} coap_proto_t;
+#define COAP_PROTO_NONE         0
+#define COAP_PROTO_UDP          1
+#define COAP_PROTO_DTLS         2
+#define COAP_PROTO_TCP          3
+#define COAP_PROTO_TLS          4
 
 /**
  * Creates a new CoAP PDU with at least enough storage space for the given
diff --git a/man/coap_encryption.txt.in b/man/coap_encryption.txt.in
index 843bc8a3..12d6e1c3 100644
--- a/man/coap_encryption.txt.in
+++ b/man/coap_encryption.txt.in
@@ -120,7 +120,7 @@ below.
 [source, c]
 ----
 typedef struct coap_dtls_pki_t {
-  coap_dtls_pki_version_t version;  /* Set to COAP_DTLS_PKI_SETUP_VERSION */
+  uint8_t version;            /* COAP_DTLS_PKI_SETUP_VERSION */
 
   /* Options to enable different TLS functionality in libcoap */
   uint8_t verify_peer_cert;         /* 1 if peer cert is to be verified */
@@ -178,12 +178,7 @@ enabled.
 *SECTION: coap_dtls_pki_t Version*
 [source, c]
 ----
-typedef enum
-{
-  COAP_DTLS_PKI_SETUP_VERSION_V1 = 1,
-  COAP_DTLS_PKI_SETUP_VERSION =
-              COAP_DTLS_PKI_SETUP_VERSION_V1, /**< Latest PKI setup version */
-} coap_dtls_pki_version_t;
+#define COAP_DTLS_PKI_SETUP_VERSION 1
 ----
 
 *version* is set to COAP_DTLS_PKI_SETUP_VERSION.  This will then allow support
diff --git a/src/net.c b/src/net.c
index 81d97ee7..6d86eb99 100644
--- a/src/net.c
+++ b/src/net.c
@@ -701,7 +701,6 @@ coap_session_send_pdu(coap_session_t *session, coap_pdu_t *pdu) {
       bytes_written = coap_tls_write(session, pdu->token - pdu->hdr_size,
                                      pdu->used_size + pdu->hdr_size);
       break;
-    case COAP_PROTO_NONE:
     default:
       break;
   }
@@ -1186,9 +1185,6 @@ coap_write_session(coap_context_t *ctx, coap_session_t *session, coap_tick_t now
           q->pdu->used_size + q->pdu->hdr_size - session->partial_write
         );
         break;
-      case COAP_PROTO_NONE:
-      case COAP_PROTO_UDP:
-      case COAP_PROTO_DTLS:
       default:
         bytes_written = -1;
         break;