diff --git a/CHANGES b/CHANGES
index 5ec4d0c..7d66962 100644
--- a/CHANGES
+++ b/CHANGES
@@ -39,6 +39,9 @@ The following are the changes from calc version 2.12.7.1 to date:
      To make calc RPMs more portable, they are compiled with an
      empty ARCH_CFLAGS.
 
+     Fixed issues relating to compiling on macOS.  Fixed issues
+     where <unistd.h> is needed.
+
 
 The following are the changes from calc version 2.12.6.10: to 2.12.7.0:
 
diff --git a/Makefile.ship b/Makefile.ship
index df38125..3689b5d 100644
--- a/Makefile.ship
+++ b/Makefile.ship
@@ -1054,7 +1054,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.3
+VERSION= 2.12.7.4
 
 # Names of shared libraries with versions
 #
@@ -2925,7 +2925,7 @@ have_const.h: have_const.c ${MAKE_FILE}
 	    ${TRUE}; \
 	fi
 
-have_offscl.h: have_offscl.c ${MAKE_FILE}
+have_offscl.h: have_offscl.c have_unistd.h ${MAKE_FILE}
 	${Q} ${RM} -f offscl_tmp have_offscl.h
 	${Q} echo 'forming have_offscl.h'
 	${Q} echo '/*' > have_offscl.h
@@ -2965,7 +2965,7 @@ have_offscl.h: have_offscl.c ${MAKE_FILE}
 	    ${TRUE}; \
 	fi
 
-have_posscl.h: have_posscl.c have_fpos.h ${MAKE_FILE}
+have_posscl.h: have_posscl.c have_fpos.h have_unistd.h ${MAKE_FILE}
 	${Q} ${RM} -f have_posscl have_posscl.o posscl_tmp have_posscl.h
 	${Q} echo 'forming have_posscl.h'
 	${Q} echo '/*' > have_posscl.h
@@ -3221,7 +3221,7 @@ have_ustat.h: have_ustat.c ${MAKE_FILE}
 	    ${TRUE}; \
 	fi
 
-have_getsid.h: have_getsid.c ${MAKE_FILE}
+have_getsid.h: have_getsid.c have_unistd.h ${MAKE_FILE}
 	${Q} ${RM} -f getsid_tmp have_getsid.h
 	${Q} echo 'forming have_getsid.h'
 	${Q} echo '/*' > have_getsid.h
@@ -3261,7 +3261,7 @@ have_getsid.h: have_getsid.c ${MAKE_FILE}
 	    ${TRUE}; \
 	fi
 
-have_getpgid.h: have_getpgid.c ${MAKE_FILE}
+have_getpgid.h: have_getpgid.c have_unistd.h ${MAKE_FILE}
 	${Q} ${RM} -f getpgid_tmp have_getpgid.h
 	${Q} echo 'forming have_getpgid.h'
 	${Q} echo '/*' > have_getpgid.h
@@ -3343,7 +3343,7 @@ have_gettime.h: have_gettime.c ${MAKE_FILE}
 	    ${TRUE}; \
 	fi
 
-have_getprid.h: have_getprid.c ${MAKE_FILE}
+have_getprid.h: have_getprid.c have_unistd.h ${MAKE_FILE}
 	${Q} ${RM} -f getprid_tmp have_getprid.h
 	${Q} echo 'forming have_getprid.h'
 	${Q} echo '/*' > have_getprid.h
diff --git a/custom/Makefile b/custom/Makefile
index 0d3752c..2de4ecc 100644
--- a/custom/Makefile
+++ b/custom/Makefile
@@ -348,7 +348,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.3
+VERSION= 2.12.7.4
 
 # Names of shared libraries with versions
 #
diff --git a/custom/Makefile.head b/custom/Makefile.head
index fe56ace..1dff4be 100644
--- a/custom/Makefile.head
+++ b/custom/Makefile.head
@@ -348,7 +348,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.3
+VERSION= 2.12.7.4
 
 # Names of shared libraries with versions
 #
diff --git a/have_getpgid.c b/have_getpgid.c
index b383a4f..c4ec173 100644
--- a/have_getpgid.c
+++ b/have_getpgid.c
@@ -1,7 +1,7 @@
 /*
  * have_getpgid - determine if we have getpgid()
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -39,7 +39,10 @@
  */
 
 #include <sys/types.h>
+#include "have_unistd.h"
+#if defined(HAVE_UNISTD_H)
 #include <unistd.h>
+#endif
 
 int
 main(void)
diff --git a/have_getprid.c b/have_getprid.c
index 03e787d..0b75f5c 100644
--- a/have_getprid.c
+++ b/have_getprid.c
@@ -1,7 +1,7 @@
 /*
  * have_getprid - determine if we have getprid()
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -40,7 +40,10 @@
 
 
 #include <sys/types.h>
+#include "have_unistd.h"
+#if defined(HAVE_UNISTD_H)
 #include <unistd.h>
+#endif
 
 int
 main(void)
diff --git a/have_getsid.c b/have_getsid.c
index bfa5d8c..b2247ec 100644
--- a/have_getsid.c
+++ b/have_getsid.c
@@ -1,7 +1,7 @@
 /*
  * have_getsid - determine if we have getsid()
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -40,6 +40,10 @@
 
 
 #include <sys/types.h>
+#include "have_unistd.h"
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
 
 int
 main(void)
diff --git a/have_memmv.c b/have_memmv.c
index f55f89f..9d06f2d 100644
--- a/have_memmv.c
+++ b/have_memmv.c
@@ -1,7 +1,7 @@
 /*
  * have_memmv - Determine if we have memmove()
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -40,6 +40,7 @@
 
 
 #include <stdio.h>
+#include <string.h>
 
 #define MOVELEN 3
 
diff --git a/have_newstr.c b/have_newstr.c
index 1f93cee..2663504 100644
--- a/have_newstr.c
+++ b/have_newstr.c
@@ -1,7 +1,7 @@
 /*
  * have_newstr - Determine if we have a system without ANSI C string functions
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -42,6 +42,7 @@
 
 
 #include <stdio.h>
+#include <string.h>
 
 #define MOVELEN 3
 
diff --git a/have_offscl.c b/have_offscl.c
index ea78164..99fc4b2 100644
--- a/have_offscl.c
+++ b/have_offscl.c
@@ -1,7 +1,7 @@
 /*
  * have_offscl - determine if we have a scalar off_t element
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -46,6 +46,10 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include "have_unistd.h"
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
 
 int
 main(void)
diff --git a/have_posscl.c b/have_posscl.c
index 11af9c5..2c3ef6b 100644
--- a/have_posscl.c
+++ b/have_posscl.c
@@ -1,7 +1,7 @@
 /*
  * have_posscl - determine if we have a scalar FILEPOS element
  *
- * Copyright (C) 1999  Landon Curt Noll
+ * Copyright (C) 1999,2021  Landon Curt Noll
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -45,6 +45,10 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include "have_unistd.h"
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
 #include "have_fpos.h"
 
 int
diff --git a/version.c b/version.c
index e3c1422..44ca543 100644
--- a/version.c
+++ b/version.c
@@ -1,7 +1,7 @@
 /*
  * version - determine the version of calc
  *
- * Copyright (C) 1999-2018  David I. Bell and Landon Curt Noll
+ * Copyright (C) 1999-2021  David I. Bell and Landon Curt Noll
  *
  * Primary author:  David I. Bell
  *
@@ -45,7 +45,7 @@ static char *program;
 #define MAJOR_VER	2	/* major library version */
 #define MINOR_VER	12	/* minor library version */
 #define MAJOR_PATCH	7	/* major software level under library version */
-#define MINOR_PATCH	3	/* minor software level or 0 if not patched */
+#define MINOR_PATCH	4	/* minor software level or 0 if not patched */
 
 
 /*
@@ -69,7 +69,7 @@ STATIC char *stored_version = NULL;	/* version formed if != NULL */
 char *Copyright = "\n"
   "calc - arbitrary precision calculator\n"
   "\n"
-  "Copyright (C) 1999-2017  David I. Bell, Landon Curt Noll "
+  "Copyright (C) 1999-2021  David I. Bell, Landon Curt Noll "
   					   "and Ernest Bowen\n"
   "\n"
   "Initial author:  David I. Bell\n"