diff --git a/lib/internal.h b/lib/internal.h
index 2aef554..20968de 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -44,6 +44,12 @@
 #endif
 #endif
 
+// Typedef DWORD (defined by pcsc lib) to pcsc_word to make it clear that this
+// is not the Windows meaning of DWORD, but the PCSC library's meaning.  This
+// differs: Windows defines a DWORD as 32-bits, but pcsclite defines it as
+// 'unsigned long' on x86_64 Linux, which is often 64-bits.
+typedef DWORD pcsc_word;
+
 #ifdef __cplusplus
 extern "C"
 {
diff --git a/lib/tests/Makefile.am b/lib/tests/Makefile.am
index 858cf1f..46264f4 100644
--- a/lib/tests/Makefile.am
+++ b/lib/tests/Makefile.am
@@ -26,7 +26,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 AM_CFLAGS = $(WARN_CFLAGS) @CHECK_CFLAGS@ $(OPENSSL_CFLAGS)
-AM_CPPFLAGS = -I$(top_srcdir)/lib -I$(top_builddir)/lib $(OPENSSL_CFLAGS)
+AM_CPPFLAGS = -I$(top_srcdir)/lib -I$(top_builddir)/lib $(OPENSSL_CFLAGS) $(PCSC_CFLAGS)
 
 AM_LDFLAGS = @CHECK_LIBS@
 
diff --git a/lib/tests/api.c b/lib/tests/api.c
index d7bf972..81ec279 100644
--- a/lib/tests/api.c
+++ b/lib/tests/api.c
@@ -40,6 +40,14 @@
 
 int destruction_confirmed(void);
 
+// only defined in libcheck 0.11+ (linux distros still shipping 0.10)
+#ifndef ck_assert_ptr_nonnull
+#define ck_assert_ptr_nonnull(a) ck_assert((a) != NULL)
+#endif
+#ifndef ck_assert_mem_eq
+#define ck_assert_mem_eq(a,b,n) ck_assert(memcmp((a), (b), (n)) == 0)
+#endif
+
 ykpiv_state *g_state;
 const uint8_t g_cert[] = {
   "0123456789ABCDEFGHIK0123456789ABCDEFGHIK0123456789ABCDEFGHIK0123456789ABCDEFGHIK"
@@ -97,12 +105,12 @@ START_TEST(test_devicemodel) {
   ck_assert_int_eq(res, YKPIV_OK);
   ck_assert_int_gt(num_readers, 0);
   if (model == DEVTYPE_YK4) {
-    ck_assert_ptr_nonnull(strnstr(reader_buf, "Yubikey 4", strlen(reader_buf)));
+    ck_assert_ptr_nonnull(strstr(reader_buf, "Yubikey 4"));
     ck_assert(version[0] == '4'); // Verify app version 4.x
     ck_assert(version[1] == '.');
   }
   else {
-    ck_assert_ptr_nonnull(strnstr(reader_buf, "Yubikey NEO", strlen(reader_buf)));
+    ck_assert_ptr_nonnull(strstr(reader_buf, "Yubikey NEO"));
     ck_assert(version[0] == '1'); // Verify app version 1.x
     ck_assert(version[1] == '.');
   }
diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 50c7340..b6d0a05 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -259,9 +259,9 @@ static ykpiv_rc _ykpiv_connect(ykpiv_state *state, uintptr_t context, uintptr_t
   // if card handle has changed, determine if handle is valid (less efficient, but complete)
   if ((card != state->card)) {
     char reader[CB_BUF_MAX];
-    uint32_t reader_len = (uint32_t)sizeof(reader);
+    pcsc_word reader_len = sizeof(reader);
     uint8_t atr[CB_ATR_MAX];
-    uint32_t atr_len = (uint32_t)sizeof(atr);
+    pcsc_word atr_len = sizeof(atr);
 
     // Cannot set the reader len to NULL.  Confirmed in OSX 10.10, so we have to retrieve it even though we don't need it.
     if (SCARD_S_SUCCESS != SCardStatus(card, reader, &reader_len, NULL, NULL, atr, &atr_len)) {
@@ -291,7 +291,7 @@ ykpiv_rc ykpiv_connect_with_external_card(ykpiv_state *state, uintptr_t context,
 }
 
 ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
-  uint32_t active_protocol;
+  pcsc_word active_protocol;
   char reader_buf[2048];
   size_t num_readers = sizeof(reader_buf);
   long rc;
@@ -316,7 +316,7 @@ ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
       fprintf(stderr, "trying to connect to reader '%s'.\n", reader_ptr);
     }
     rc = SCardConnect(state->context, reader_ptr, SCARD_SHARE_SHARED,
-        SCARD_PROTOCOL_T1, &card, &active_protocol);
+		      SCARD_PROTOCOL_T1, &card, &active_protocol);
     if(rc != SCARD_S_SUCCESS)
     {
       if(state->verbose) {
@@ -352,7 +352,7 @@ ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
 }
 
 static ykpiv_rc reconnect(ykpiv_state *state) {
-  uint32_t active_protocol;
+  pcsc_word active_protocol;
   long rc;
   ykpiv_rc res;
   int tries;
@@ -360,7 +360,7 @@ static ykpiv_rc reconnect(ykpiv_state *state) {
     fprintf(stderr, "trying to reconnect to current reader.\n");
   }
   rc = SCardReconnect(state->card, SCARD_SHARE_SHARED,
-    SCARD_PROTOCOL_T1, SCARD_RESET_CARD, &active_protocol);
+		      SCARD_PROTOCOL_T1, SCARD_RESET_CARD, &active_protocol);
   if(rc != SCARD_S_SUCCESS) {
     if(state->verbose) {
       fprintf(stderr, "SCardReconnect failed, rc=%08lx\n", rc);
@@ -377,7 +377,7 @@ static ykpiv_rc reconnect(ykpiv_state *state) {
 }
 
 ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len) {
-  uint32_t num_readers = 0;
+  pcsc_word num_readers = 0;
   long rc;
 
   if(SCardIsValidContext(state->context) != SCARD_S_SUCCESS) {
@@ -531,19 +531,21 @@ static ykpiv_rc _send_data(ykpiv_state *state, APDU *apdu,
     unsigned char *data, uint32_t *recv_len, int *sw) {
   long rc;
   unsigned int send_len = (unsigned int)apdu->st.lc + 5;
+  pcsc_word tmp_len = *recv_len;
 
   if(state->verbose > 1) {
     fprintf(stderr, "> ");
     dump_hex(apdu->raw, send_len);
     fprintf(stderr, "\n");
   }
-  rc = SCardTransmit(state->card, SCARD_PCI_T1, apdu->raw, send_len, NULL, data, recv_len);
+  rc = SCardTransmit(state->card, SCARD_PCI_T1, apdu->raw, send_len, NULL, data, &tmp_len);
   if(rc != SCARD_S_SUCCESS) {
     if(state->verbose) {
       fprintf (stderr, "error: SCardTransmit failed, rc=%08lx\n", rc);
     }
     return YKPIV_PCSC_ERROR;
   }
+  *recv_len = (uint32_t)tmp_len;
 
   if(state->verbose > 1) {
     fprintf(stderr, "< ");
diff --git a/lib/ykpiv.map b/lib/ykpiv.map
index 4f013aa..5381cb7 100644
--- a/lib/ykpiv.map
+++ b/lib/ykpiv.map
@@ -79,37 +79,37 @@ global:
 YKPIV_1.5.0
 {
 global:
-    ykpiv_attest
-    ykpiv_auth_getchallenge
-    ykpiv_auth_verifyresponse
-    ykpiv_connect_with_external_card
-    ykpiv_done_with_external_card
-    ykpiv_get_pin_retries
-    ykpiv_init_with_allocator
-    ykpiv_set_pin_retries
-    ykpiv_util_block_puk
-    ykpiv_util_delete_cert
-    ykpiv_util_devicemodel
-    ykpiv_util_free
-    ykpiv_util_generate_key
-    ykpiv_util_get_cardid
-    ykpiv_util_get_cccid
-    ykpiv_util_get_config
-    ykpiv_util_get_derived_mgm
-    ykpiv_util_get_protected_mgm
-    ykpiv_util_list_keys
-    ykpiv_util_list_keys.SLOTS
-    ykpiv_util_read_cert
-    ykpiv_util_read_mscmap
-    ykpiv_util_read_msroots
-    ykpiv_util_reset
-    ykpiv_util_set_cardid
-    ykpiv_util_set_cccid
-    ykpiv_util_set_pin_last_changed
-    ykpiv_util_set_protected_mgm
-    ykpiv_util_slot_object
-    ykpiv_util_write_cert
-    ykpiv_util_write_mscmap
-    ykpiv_util_write_msroots
-    ykpiv_verify_select
-} YKPIV_1.5.0;
+    ykpiv_attest;
+    ykpiv_auth_getchallenge;
+    ykpiv_auth_verifyresponse;
+    ykpiv_connect_with_external_card;
+    ykpiv_done_with_external_card;
+    ykpiv_get_pin_retries;
+    ykpiv_init_with_allocator;
+    ykpiv_set_pin_retries;
+    ykpiv_util_block_puk;
+    ykpiv_util_delete_cert;
+    ykpiv_util_devicemodel;
+    ykpiv_util_free;
+    ykpiv_util_generate_key;
+    ykpiv_util_get_cardid;
+    ykpiv_util_get_cccid;
+    ykpiv_util_get_config;
+    ykpiv_util_get_derived_mgm;
+    ykpiv_util_get_protected_mgm;
+    ykpiv_util_list_keys;
+    ykpiv_util_list_keys;
+    ykpiv_util_read_cert;
+    ykpiv_util_read_mscmap;
+    ykpiv_util_read_msroots;
+    ykpiv_util_reset;
+    ykpiv_util_set_cardid;
+    ykpiv_util_set_cccid;
+    ykpiv_util_set_pin_last_changed;
+    ykpiv_util_set_protected_mgm;
+    ykpiv_util_slot_object;
+    ykpiv_util_write_cert;
+    ykpiv_util_write_mscmap;
+    ykpiv_util_write_msroots;
+    ykpiv_verify_select;
+} YKPIV_1.3.0;