diff --git a/lib/internal.c b/lib/internal.c
index 9e6c33b..30e5601 100644
--- a/lib/internal.c
+++ b/lib/internal.c
@@ -377,7 +377,7 @@ bool yk_des_is_weak_key(const unsigned char *key, const size_t cb_key) {
   return false;
 }
 
-prng_rc prng_generate(unsigned char *buffer, const size_t cb_req) {
+prng_rc _ykpiv_prng_generate(unsigned char *buffer, const size_t cb_req) {
   prng_rc rc = PRNG_OK;
 
 #ifdef _WINDOWS
diff --git a/lib/internal.h b/lib/internal.h
index 66ab628..f6ade36 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -130,9 +130,13 @@ des_rc des_import_key(const int type, const unsigned char* keyraw, const size_t
 des_rc des_destroy_key(des_key* key);
 des_rc des_encrypt(des_key* key, const unsigned char* in, const size_t inlen, unsigned char* out, size_t* outlen);
 des_rc des_decrypt(des_key* key, const unsigned char* in, const size_t inlen, unsigned char* out, size_t* outlen);
-bool   yk_des_is_weak_key(const unsigned char *key, const size_t cb_key);
 pkcs5_rc pkcs5_pbkdf2_sha1(const unsigned char* password, const size_t cb_password, const unsigned char* salt, const size_t cb_salt, unsigned long long iterations, unsigned char* key, const size_t cb_key);
-prng_rc prng_generate(unsigned char *buffer, const size_t cb_req);
+bool   yk_des_is_weak_key(const unsigned char *key, const size_t cb_key);
+
+prng_rc _ykpiv_prng_generate(unsigned char *buffer, const size_t cb_req);
+ykpiv_rc _ykpiv_begin_transaction(ykpiv_state *state);
+ykpiv_rc _ykpiv_end_transaction(ykpiv_state *state);
+ykpiv_rc _ykpiv_ensure_application_selected(ykpiv_state *state);
 
 #ifdef __cplusplus
 }
diff --git a/lib/util.c b/lib/util.c
index 12e2c03..91309cf 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -117,9 +117,6 @@ void* _ykpiv_realloc(ykpiv_state *state, void *address, size_t size);
 void _ykpiv_free(ykpiv_state *state, void *data);
 int _ykpiv_set_length(unsigned char *buffer, size_t length);
 int _ykpiv_get_length(const unsigned char *buffer, size_t *len);
-ykpiv_rc _ykpiv_begin_transaction(ykpiv_state *state);
-ykpiv_rc _ykpiv_end_transaction(ykpiv_state *state);
-ykpiv_rc _ykpiv_ensure_application_selected(ykpiv_state *state);
 
 static ykpiv_rc _read_metadata(ykpiv_state *state, uint8_t tag, uint8_t* data, size_t* pcb_data);
 static ykpiv_rc _write_metadata(ykpiv_state *state, uint8_t tag, uint8_t *data, size_t cb_data);
@@ -165,7 +162,7 @@ ykpiv_rc ykpiv_util_set_cardid(ykpiv_state *state, const ykpiv_cardid *cardid) {
   if (!state) return YKPIV_GENERIC_ERROR;
 
   if (!cardid) {
-    if (PRNG_OK != prng_generate(id, sizeof(id))) {
+    if (PRNG_OK != _ykpiv_prng_generate(id, sizeof(id))) {
       return YKPIV_RANDOMNESS_ERROR;
     }
   }
@@ -384,7 +381,7 @@ ykpiv_rc ykpiv_util_block_puk(ykpiv_state *state) {
   if (YKPIV_OK != (res = _ykpiv_ensure_application_selected(state))) goto Cleanup;
 
   while (tries != 0) {
-    if (YKPIV_OK == (res = ykpiv_change_puk(state, puk, sizeof(puk), puk, sizeof(puk), &tries))) {
+    if (YKPIV_OK == (res = ykpiv_change_puk(state, (const char*)puk, sizeof(puk), (const char*)puk, sizeof(puk), &tries))) {
       /* did we accidentally choose the correct PUK?, change our puk and try again */
       puk[0]++;
     }
@@ -1125,7 +1122,7 @@ ykpiv_rc ykpiv_util_set_protected_mgm(ykpiv_state *state, ykpiv_mgm *mgm) {
   do {
     if (fGenerate) {
       /* generate a new mgm key */
-      if (PRNG_OK != (prngrc = prng_generate(mgm_key, sizeof(mgm_key)))) {
+      if (PRNG_OK != (prngrc = _ykpiv_prng_generate(mgm_key, sizeof(mgm_key)))) {
         if (state->verbose) fprintf(stderr, "could not set generate new mgm, err = %d\n", prngrc);
         res = YKPIV_RANDOMNESS_ERROR;
         goto Cleanup;
diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 02ab7f6..f29898e 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -39,8 +39,10 @@
 
 #define YKPIV_MGM_DEFAULT "\x01\x02\x03\x04\x05\x06\x07\x08\x01\x02\x03\x04\x05\x06\x07\x08\x01\x02\x03\x04\x05\x06\x07\x08"
 
+static ykpiv_rc _cache_pin(ykpiv_state *state, const char *pin, size_t len);
+
 static ykpiv_rc _send_data(ykpiv_state *state, APDU *apdu,
-    unsigned char *data, unsigned long *recv_len, int *sw);
+    unsigned char *data, uint32_t *recv_len, int *sw);
 
 unsigned const char aid[] = {
 	0xa0, 0x00, 0x00, 0x03, 0x08
@@ -189,7 +191,7 @@ ykpiv_rc ykpiv_disconnect(ykpiv_state *state) {
 ykpiv_rc _ykpiv_select_application(ykpiv_state *state) {
   APDU apdu;
   unsigned char data[0xff];
-  unsigned long recv_len = sizeof(data);
+  uint32_t recv_len = sizeof(data);
   int sw;
   ykpiv_rc res;
 
@@ -277,7 +279,7 @@ ykpiv_rc ykpiv_connect_with_card(ykpiv_state *state, uint64_t context, uint64_t
 
 ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
   // TREV TODO: use _connect_internal
-  unsigned long active_protocol;
+  uint32_t active_protocol;
   char reader_buf[2048];
   size_t num_readers = sizeof(reader_buf);
   long rc;
@@ -330,7 +332,7 @@ ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
 }
 
 static ykpiv_rc reconnect(ykpiv_state *state) {
-  unsigned long active_protocol;
+  uint32_t active_protocol;
   long rc;
   ykpiv_rc res;
   int tries;
@@ -355,7 +357,7 @@ static ykpiv_rc reconnect(ykpiv_state *state) {
 }
 
 ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len) {
-  unsigned long num_readers = 0;
+  uint32_t num_readers = 0;
   long rc;
 
   if(SCardIsValidContext(state->context) != SCARD_S_SUCCESS) {
@@ -442,7 +444,7 @@ ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
   do {
     size_t this_size = 0xff;
     unsigned char data[261];
-    unsigned long recv_len = sizeof(data);
+    uint32_t recv_len = sizeof(data);
     APDU apdu;
 
     memset(apdu.raw, 0, sizeof(apdu.raw));
@@ -481,7 +483,7 @@ ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
   while(*sw >> 8 == 0x61) {
     APDU apdu;
     unsigned char data[261];
-    unsigned long recv_len = sizeof(data);
+    uint32_t recv_len = sizeof(data);
 
     if(state->verbose > 2) {
       fprintf(stderr, "The card indicates there is %d bytes more data for us.\n", *sw & 0xff);
@@ -509,7 +511,7 @@ ykpiv_rc ykpiv_transfer_data(ykpiv_state *state, const unsigned char *templ,
 }
 
 static ykpiv_rc _send_data(ykpiv_state *state, APDU *apdu,
-    unsigned char *data, unsigned long *recv_len, int *sw) {
+    unsigned char *data, uint32_t *recv_len, int *sw) {
   long rc;
   unsigned int send_len = (unsigned int)apdu->st.lc + 5;
 
@@ -543,7 +545,7 @@ ykpiv_rc ykpiv_authenticate(ykpiv_state *state, unsigned const char *key) {
   APDU apdu;
   unsigned char data[261];
   unsigned char challenge[8];
-  unsigned long recv_len = sizeof(data);
+  uint32_t recv_len = sizeof(data);
   int sw;
   ykpiv_rc res;
   des_key* mgm_key = NULL;
@@ -553,7 +555,7 @@ ykpiv_rc ykpiv_authenticate(ykpiv_state *state, unsigned const char *key) {
 
   if (NULL == key) {
     /* use the derived mgm key to authenticate, if it hasn't been derived, use default */
-    key = YKPIV_MGM_DEFAULT;
+    key = (unsigned const char*)YKPIV_MGM_DEFAULT;
   }
 
   /* set up our key */
@@ -602,7 +604,7 @@ ykpiv_rc ykpiv_authenticate(ykpiv_state *state, unsigned const char *key) {
     dataptr += 8;
     *dataptr++ = 0x81;
     *dataptr++ = 8;
-    if (PRNG_GENERAL_ERROR == prng_generate(dataptr, 8)) {
+    if (PRNG_GENERAL_ERROR == _ykpiv_prng_generate(dataptr, 8)) {
       if (state->verbose) {
         fprintf(stderr, "Failed getting randomness for authentication.\n");
       }
@@ -650,7 +652,7 @@ ykpiv_rc ykpiv_set_mgmkey(ykpiv_state *state, const unsigned char *new_key) {
 ykpiv_rc ykpiv_set_mgmkey2(ykpiv_state *state, const unsigned char *new_key, const unsigned char touch) {
   APDU apdu;
   unsigned char data[261];
-  unsigned long recv_len = sizeof(data);
+  uint32_t recv_len = sizeof(data);
   int sw;
   ykpiv_rc res = YKPIV_OK;
 
@@ -868,7 +870,7 @@ Cleanup:
 ykpiv_rc ykpiv_get_version(ykpiv_state *state, char *version, size_t len) {
   APDU apdu;
   unsigned char data[261];
-  unsigned long recv_len = sizeof(data);
+  uint32_t recv_len = sizeof(data);
   int sw;
   ykpiv_rc res;
 
@@ -887,7 +889,7 @@ ykpiv_rc ykpiv_get_version(ykpiv_state *state, char *version, size_t len) {
   }
 }
 
-ykpiv_rc _cache_pin(ykpiv_state *state, const char *pin, size_t len) {
+static ykpiv_rc _cache_pin(ykpiv_state *state, const char *pin, size_t len) {
 #ifdef DISABLE_PIN_CACHE
   // Some embedded applications of this library may not want to keep the PIN
   // data in RAM for security reasons.
@@ -914,7 +916,7 @@ ykpiv_rc ykpiv_verify(ykpiv_state *state, const char *pin, int *tries) {
   // TREV TODO: pin len?
   APDU apdu;
   unsigned char data[261];
-  unsigned long recv_len = sizeof(data);
+  uint32_t recv_len = sizeof(data);
   int sw;
   size_t len = 0;
   ykpiv_rc res;
@@ -1275,7 +1277,7 @@ ykpiv_rc ykpiv_done2(ykpiv_state *state, bool disconnect) {
   return YKPIV_OK;
 }
 
-ykpiv_rc ykpiv_verify_select(ykpiv_state *state, const uint8_t *pin, const size_t pin_len, int *tries, bool force_select) {
+ykpiv_rc ykpiv_verify_select(ykpiv_state *state, const char *pin, const size_t pin_len, int *tries, bool force_select) {
   ykpiv_rc res = YKPIV_OK;
   if (YKPIV_OK != (res = _ykpiv_begin_transaction(state))) goto Cleanup;
 #if 0
diff --git a/lib/ykpiv.h b/lib/ykpiv.h
index b0f3081..637f655 100644
--- a/lib/ykpiv.h
+++ b/lib/ykpiv.h
@@ -456,7 +456,7 @@ extern "C"
 
   // TREV TODO: remove
   ykpiv_rc ykpiv_done2(ykpiv_state *state, bool disconnect);
-  ykpiv_rc ykpiv_verify_select(ykpiv_state *state, const uint8_t *pin, const size_t pin_len, int *tries, bool force_select);
+  ykpiv_rc ykpiv_verify_select(ykpiv_state *state, const char *pin, const size_t pin_len, int *tries, bool force_select);
 
 #ifdef __cplusplus
 }