diff --git a/.gitignore b/.gitignore
index b1ce3af..7f8ac6f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 .svn
 *.o
+*~
 aclocal.m4
 autom4te.cache/*
 compile
diff --git a/configure.ac b/configure.ac
index 22b4e2b..78eed80 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,7 +30,6 @@ AC_TYPE_UINT8_T
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 
-AC_CHECK_HEADERS([sys/time.h])
 AC_CHECK_FUNCS([memset strchr strtoul])
 
 # Checks for endianness convertion
@@ -41,6 +40,9 @@ fi
 
 AC_CHECK_HEADERS([byteswap.h])
 
+AC_CHECK_HEADERS([unistd.h])
+AM_CONDITIONAL([HAVE_UNISTD], [test $ac_cv_header_unistd_h = "yes"])
+
 AC_DEFINE([_XOPEN_SOURCE], [600], [Define to 500 if Single Unix conformance is wanted, 600 for sixth revision.])
 
 # Help us to write great code ;-)
diff --git a/src/Makefile.am b/src/Makefile.am
index f8cebf4..97c5b02 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -2,9 +2,14 @@ AM_CFLAGS  = @libnfc_CFLAGS@
 
 bin_PROGRAMS = mfcuk
 
-noinst_HEADERS = crapto1.h mifare.h nfc-utils.h mfcuk_mifare.h mfcuk_finger.h mfcuk_utils.h xgetopt.h mfcuk.h
+noinst_HEADERS = crapto1.h mifare.h nfc-utils.h mfcuk_mifare.h mfcuk_finger.h mfcuk_utils.h mfcuk.h xgetopt.h
 
-mfcuk_SOURCES = crapto1.c crypto1.c mifare.c nfc-utils.c mfcuk_mifare.c mfcuk_finger.c mfcuk_utils.c xgetopt.c mfcuk.c 
+mfcuk_SOURCES = crapto1.c crypto1.c mifare.c nfc-utils.c mfcuk_mifare.c mfcuk_finger.c mfcuk_utils.c mfcuk.c
 mfcuk_LDADD = @libnfc_LIBS@
 
+# If system does not have unistd.h, use our own getopt function from xgetopt.c
+if ! HAVE_UNISTD
+mfcuk_SOURCES += xgetopt.c
+endif
+
 # dist_man_MANS = mfcuk.1
diff --git a/src/mfcuk.c b/src/mfcuk.c
index fa38d1d..9339f59 100644
--- a/src/mfcuk.c
+++ b/src/mfcuk.c
@@ -174,15 +174,7 @@ static inline uint64_t bswap_64(uint64_t x)
 #include <err.h>
 #include <errno.h>
 
-#ifdef WIN32
-#define NOMINMAX
-#include "windows.h"
 #include "xgetopt.h"
-#elif __STDC__
-#include <unistd.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#endif
 
 // NFC
 #include <nfc/nfc.h>
@@ -497,7 +489,7 @@ static uint32_t mfcuk_key_recovery_block(nfc_device *pnd, uint32_t uiUID, uint64
     if (ptrFoundTagNonceEntry->current_out_of_8 >= MFCUK_DARKSIDE_MAX_LEVELS)
     {
         //printf("FAILURE - This Nt, {Pfx}, consecutive {Nr}s and {ParBits} combination cannot produce a key-recoverable state\n");
-        //printf("\tINFO: try changing initial {Nr}, {Ar} and timings of sleep()\n");
+        //printf("\tINFO: try changing initial {Nr}, {Ar} and timings of sleepmillis()\n");
 
         //printf("{Nr} is not a DEADBEEF.... Need to find BEEF ALIVE!... Trying next one...\n");
         ptrFoundTagNonceEntry->spoofNrEnc++;
@@ -516,7 +508,7 @@ static uint32_t mfcuk_key_recovery_block(nfc_device *pnd, uint32_t uiUID, uint64
         if (ptrFoundTagNonceEntry->parBitsCrntCombination[ptrFoundTagNonceEntry->current_out_of_8] >= 0x20)
         {
             //printf("FAILURE - This consecutive {Nr}s and {ParBits} combination cannot produce all 8 required NACKs and KSs of NACKs\n");
-            //printf("\tINFO: try changing initial {Nr}, {Ar} and timings of sleep()\n");
+            //printf("\tINFO: try changing initial {Nr}, {Ar} and timings of sleepmillis()\n");
 
             //printf("{Nr} is not a DEADBEEF.... Need to find BEEF ALIVE!... Trying next one...\n");
             ptrFoundTagNonceEntry->spoofNrEnc++;
@@ -838,7 +830,7 @@ static bool mfcuk_darkside_select_tag(nfc_device *pnd, int iSleepAtFieldOFF, int
   }
 
   // {WPMCC09} 2.4. Tag nonces: "drop the field (for approximately 30us) to discharge all capacitors"
-  sleep(iSleepAtFieldOFF);
+  sleepmillis(iSleepAtFieldOFF);
 
   // Let the reader only try once to find a tag
   if (0 > nfc_device_set_property_bool(pnd, NP_INFINITE_SELECT, false)) {
@@ -864,7 +856,7 @@ static bool mfcuk_darkside_select_tag(nfc_device *pnd, int iSleepAtFieldOFF, int
   }
 
   // Switch the field back on, and wait for a constant amount of time before authenticating
-  sleep(iSleepAfterFieldON);
+  sleepmillis(iSleepAfterFieldON);
 
   // Poll for a ISO14443A (MIFARE) tag
   if (0 >= nfc_initiator_select_passive_target(pnd, nmMifare, NULL, 0, &ti_tmp)) {
diff --git a/src/mfcuk_utils.c b/src/mfcuk_utils.c
index 586d2ab..4d8f2e6 100644
--- a/src/mfcuk_utils.c
+++ b/src/mfcuk_utils.c
@@ -45,12 +45,19 @@
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include "mfcuk_utils.h"
+#include "config.h"
 
-#ifdef __STDC__
-struct timeval global_timeout;
+#if defined(WIN32)
+#include <windows.h>
+#elif defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#else
+#error "Unsupported system"
 #endif
 
+#include "mfcuk_utils.h"
+#include <stdio.h>
+
 /*
 http://www.velocityreviews.com/forums/t451319-advice-required-on-my-ascii-to-hex-conversion-c.html
 Basically, converting a hex digit into a hex nibble (4 binary digits) algorithm looks like;
@@ -79,3 +86,22 @@ unsigned char hex2bin(unsigned char h, unsigned char l)
   l -= -(l > 9) & 0x27;
   return h << 4 | l;
 }
+
+void sleepmillis(unsigned int millis)
+{
+#ifdef WIN32 // If system is Windows, use system's own function if possible to reduce overhead, even if a standard C library is available
+  Sleep(millis);
+#else
+  usleep(millis * 1000);
+#endif
+}
+
+void clear_screen()
+{
+#ifdef WIN32 // On Windows, use "cls" command
+  system("cls");
+#else // Otherwise fall back to TTY control characters
+  printf("\033[1;1H\033[J");
+#endif
+}
+
diff --git a/src/mfcuk_utils.h b/src/mfcuk_utils.h
index b404344..73195b6 100644
--- a/src/mfcuk_utils.h
+++ b/src/mfcuk_utils.h
@@ -48,35 +48,6 @@
 #ifndef _MFCUK_UTILS_H_
 #define _MFCUK_UTILS_H_
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#ifdef WIN32
-#define NOMINMAX
-#include "windows.h"
-#include "xgetopt.h"
-#elif __STDC__
-#include <unistd.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#endif
-
-// "Portable" sleep(miliseconds)
-#ifdef WIN32
-#define sleep(x) Sleep(x)
-#elif __STDC__
-extern struct timeval global_timeout;
-#define sleep(x) { global_timeout.tv_usec = 1000 * (x); select(0,NULL,NULL,NULL,&global_timeout); }
-#endif
-
-// "Portable" clear_screen() - NOTE: system performance penalty introduced
-#ifdef WIN32
-#define clear_screen()  system("cls")
-#elif __STDC__
-#define clear_screen()  system("sh -c clear")
-#endif
-
 /**
  * @fn int is_hex(char c)
  * @brief Checks if an ASCII character is a valid hexadecimal base digit
@@ -101,4 +72,23 @@ int is_hex(char c);
  */
 unsigned char hex2bin(unsigned char h, unsigned char l);
 
+/**
+ * @fn void sleepmillis(unsigned int millis)
+ * @brief Pauses execution for a certain amount of milliseconds
+ * @param millis Number of milliseconds to sleep
+ *
+ * Wrapper for system-dependant sleep function. It pauses execution for a certain amount of milliseconds.
+ */
+void sleepmillis(unsigned int millis);
+
+/**
+ * @fn void clear_screen(void);
+ * @brief Clears output console
+ *
+ * Wrapper for system-dependant clear screen function.
+ * Resets output console, clearing text and resetting character pointer.
+ */
+void clear_screen(void);
+
 #endif // _MFCUK_UTILS_H_
+
diff --git a/src/xgetopt.h b/src/xgetopt.h
index fa6f6ad..fabf5fd 100644
--- a/src/xgetopt.h
+++ b/src/xgetopt.h
@@ -15,9 +15,15 @@
 #ifndef XGETOPT_H
 #define XGETOPT_H
 
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#else
+
 extern int optind, opterr;
 extern char *optarg;
 
 int getopt(int argc, char *argv[], char *optstring);
 
+#endif
+
 #endif //XGETOPT_H