diff --git a/src/intcmp.c b/src/intcmp.c
index fc7e0e9..e5dcdec 100644
--- a/src/intcmp.c
+++ b/src/intcmp.c
@@ -18,9 +18,9 @@
 
 #include <errno.h> /* errno */
 #include <stdio.h> /* fprintf(3), stderr */
-#include <stdlib.h> /* strtol(3), size_t */
+#include <stdlib.h> /* strtol(3), size_t, EXIT_FAILURE */
 #ifndef EX_USAGE
-#	include <sysexits.h> /* EX_USAGE */
+#	define EX_USAGE EXIT_FAILURE
 #endif
 #include <unistd.h> /* getopt(3), optind */
 
diff --git a/src/npc.c b/src/npc.c
index c927d28..8a07f1e 100644
--- a/src/npc.c
+++ b/src/npc.c
@@ -18,9 +18,13 @@
 
 #include <stdio.h> /* fprintf(3), fputs(3), getc(3), putc(3), stdin, stdout,
                     * EOF */
+#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
 #include <unistd.h> /* getopt(3) */
-#if !defined EX_USAGE || !defined EX_OK
-#	include <sysexits.h>
+#if !defined EX_USAGE
+#	define EX_USAGE EXIT_FAILURE
+#endif
+#if !defined EX_OK
+#	define EX_OK EXIT_SUCCESS
 #endif
 
 int main(int argc, char *argv[]){
diff --git a/src/scrut.c b/src/scrut.c
index 4cff59d..f2fc302 100644
--- a/src/scrut.c
+++ b/src/scrut.c
@@ -17,9 +17,10 @@
  */
 
 #include <stdio.h> /* fprintf(3), stderr, NULL */
+#include <stdlib.h> /* EXIT_FAILURE */
 #include <string.h> /* strchr(3) */
 #ifndef EX_USAGE
-#	include <sysexits.h>
+#	define EX_USAGE EXIT_FAILURE
 #endif
 #include <unistd.h> /* access(3), getopt(3), F_OK, R_OK, W_OK, X_OK */
 #include <sys/stat.h> /* lstat(3), stat struct, S_ISBLK, S_ISCHR, S_ISDIR,
diff --git a/src/str.c b/src/str.c
index 2f38ec1..583422d 100644
--- a/src/str.c
+++ b/src/str.c
@@ -20,9 +20,10 @@
 #include <ctype.h>
 #include <stddef.h> /* NULL */
 #include <stdio.h> /* fprintf(3) */
+#include <stdlib.h> /* EXIT_FAILURE */
 #include <string.h> /* strcmp(3) */
 #if !defined EX_USAGE
-#	include <sysexits.h>
+#	define EX_USAGE EXIT_FAILURE
 #endif
 
 static char *program_name = "str";
diff --git a/src/strcmp.c b/src/strcmp.c
index d2fbc2b..76a2681 100644
--- a/src/strcmp.c
+++ b/src/strcmp.c
@@ -1,6 +1,7 @@
 #include <stdio.h> /* fprintf(3), stderr */
-#ifndef EX_USAGE
-#	include <sysexits.h> /* EX_USAGE */
+#include <stdlib.h> /* EXIT_FAILURE */
+#if !defined EX_USAGE
+#	define EX_USAGE EXIT_FAILURE
 #endif
 
 static char *program_name = "strcmp";