diff --git a/lib/internal.c b/lib/internal.c
index 6251924..e8942b3 100644
--- a/lib/internal.c
+++ b/lib/internal.c
@@ -2,8 +2,6 @@
 #ifdef _WINDOWS
 #include <windows.h>
 #include <wincrypt.h>
-#include <ntstatus.h>
-#define WIN32_NO_STATUS
 #include <bcrypt.h>
 #else
 #include <openssl/des.h>
@@ -23,6 +21,8 @@
 
 #ifdef _WINDOWS
 
+#define STATUS_SUCCESS                   ((NTSTATUS)0x00000000L) 
+
 struct des_key {
   HCRYPTPROV hProv;
   HCRYPTKEY  hKey;
diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 01723f9..50c7340 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -97,16 +97,16 @@ static void dump_hex(const unsigned char *buf, unsigned int len) {
 
 int _ykpiv_set_length(unsigned char *buffer, size_t length) {
   if(length < 0x80) {
-    *buffer++ = length;
+    *buffer++ = (unsigned char)length;
     return 1;
   } else if(length < 0xff) {
     *buffer++ = 0x81;
-    *buffer++ = length;
+    *buffer++ = (unsigned char)length;
     return 2;
   } else {
     *buffer++ = 0x82;
     *buffer++ = (length >> 8) & 0xff;
-    *buffer++ = length & 0xff;
+    *buffer++ = (unsigned char)length & 0xff;
     return 3;
   }
 }
@@ -244,7 +244,7 @@ ykpiv_rc _ykpiv_ensure_application_selected(ykpiv_state *state) {
   return res;
 }
 
-static ykpiv_rc _ykpiv_connect(ykpiv_state *state, uint64_t context, uint64_t card) {
+static ykpiv_rc _ykpiv_connect(ykpiv_state *state, uintptr_t context, uintptr_t card) {
   ykpiv_rc res = YKPIV_OK;
 
   if (NULL == state) {
@@ -286,7 +286,7 @@ static ykpiv_rc _ykpiv_connect(ykpiv_state *state, uint64_t context, uint64_t ca
   return res;
 }
 
-ykpiv_rc ykpiv_connect_with_external_card(ykpiv_state *state, uint64_t context, uint64_t card) {
+ykpiv_rc ykpiv_connect_with_external_card(ykpiv_state *state, uintptr_t context, uintptr_t card) {
   return _ykpiv_connect(state, context, card);
 }
 
diff --git a/lib/ykpiv.h b/lib/ykpiv.h
index f41367b..142b24f 100644
--- a/lib/ykpiv.h
+++ b/lib/ykpiv.h
@@ -413,7 +413,7 @@ extern "C"
    *
    * @return Error code
    */
-  ykpiv_rc ykpiv_connect_with_external_card(ykpiv_state *state, uint64_t context, uint64_t card);
+  ykpiv_rc ykpiv_connect_with_external_card(ykpiv_state *state, uintptr_t context, uintptr_t card);
 
   /**
    * Variant of ykpiv_done() for external cards connected with ykpiv_connect_with_external_card()