diff --git a/CHANGES b/CHANGES
index 0d5f243..ec3db01 100644
--- a/CHANGES
+++ b/CHANGES
@@ -89,7 +89,8 @@ The following are the changes from calc version 2.14.3.1 to date:
 
     Under macOS, to reduce dependency chains, we remove functions and
     data that are unreachable by the entry point or exported symbols.
-    In particular, the linker is run with "-dead_strip".
+    In particular, the linker is run with "-dead_strip" and with
+    "-dead_strip_dylibs".
 
 
 The following are the changes from calc version 2.14.2.1 to 2.14.3.0:
diff --git a/Makefile.target b/Makefile.target
index c64be88..09dbe39 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -165,14 +165,7 @@ LIBCUSTCALC_SHLIB= -dynamiclib -undefined dynamic_lookup \
 # To reduce dependency chains under macOS, we remove functions and
 # data that are unreachable by the entry point or exported symbols.
 #
-LDFLAGS+= -Wl,-dead_strip
-
-# NOTE: Do not use: LDFLAGS+= -Wl,-dead_strip_dylibs
-#
-#	This option should not be used when linking against a dylib which is
-#	required at runtime for some indirect reason such as the dylib has an
-#	important initializer.  The libcalc and libcustcalc have
-#	important initializers, and so this option should not be used.
+LDFLAGS+= -Wl,-dead_strip -Wl,-dead_strip_dylibs
 
 # static library option
 #
diff --git a/custom.c b/custom.c
index 58f0d15..6e0e9db 100644
--- a/custom.c
+++ b/custom.c
@@ -91,6 +91,16 @@ custom(char *name, int count, VALUE **vals)
 		}
 	}
 
+	/*
+	 * validate custtbl_allowed value
+	 */
+	if (custtbl_allowed == 0) {
+	    fprintf(stderr,
+		"%sCalc was built with custom functions enabled but custtbl_allowed is 0\n",
+		(conf->tab_ok ? "\t" : ""));
+	    return error_value(E_NO_CUSTOM);
+	}
+
 	/*
 	 * no such custom function
 	 */
@@ -107,6 +117,15 @@ custom(char *name, int count, VALUE **vals)
 		    (conf->tab_ok ? "\t" : ""), name, count,
 		    (vals == NULL) ? "NULL" : "non-NULL");
 	}
+
+	/*
+	 * validate custtbl_allowed value
+	 */
+	if (custtbl_allowed != 0) {
+	    fprintf(stderr,
+		"%sCalc was built with custom functions disabled but custtbl_allowed is != 0\n",
+		(conf->tab_ok ? "\t" : ""));
+	}
 	return error_value(E_NO_CUSTOM);
 
 #endif /* CUSTOM */
diff --git a/custom.h b/custom.h
index a694c3b..42d246f 100644
--- a/custom.h
+++ b/custom.h
@@ -73,6 +73,7 @@ struct custom {
  *
  * These are the required interfaces.  The dummy.c stubs these interfaces too.
  */
+EXTERN int custtbl_allowed;		/* 1 ==> CUSTOM defined, 0 ==> CUSTOM undefined */
 E_FUNC VALUE custom(char*, int, VALUE**);	/* master custom interface */
 EXTERN BOOL allow_custom;		/* TRUE => custom builtins allowed */
 E_FUNC void showcustom(void);		/* print custom functions */
diff --git a/custom/c_argv.c b/custom/c_argv.c
index c9bb6e2..8497eaa 100644
--- a/custom/c_argv.c
+++ b/custom/c_argv.c
@@ -1,7 +1,7 @@
 /*
  * c_argv - a custom function display info about its args
  *
- * Copyright (C) 1999-2006,2021  Landon Curt Noll
+ * Copyright (C) 1999-2006,2021,2023  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
@@ -32,7 +32,7 @@
 #if defined(CUSTOM)
 int c_argv_allowed = 1;		/* CUSTOM defined */
 #else /* CUSTOM */
-int c_argv_allowed = 0;		/* CUSTOM defined */
+int c_argv_allowed = 0;		/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_devnull.c b/custom/c_devnull.c
index 89d2e40..dbb11b5 100644
--- a/custom/c_devnull.c
+++ b/custom/c_devnull.c
@@ -1,7 +1,7 @@
 /*
  * c_devnull - a custom function that does nothing
  *
- * Copyright (C) 1999-2004,2021  Landon Curt Noll
+ * Copyright (C) 1999-2004,2021,2023  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
@@ -32,7 +32,7 @@
 #if defined(CUSTOM)
 int c_devnull_allowed = 1;	/* CUSTOM defined */
 #else /* CUSTOM */
-int c_devnull_allowed = 0;	/* CUSTOM defined */
+int c_devnull_allowed = 0;	/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_help.c b/custom/c_help.c
index 52eb1d0..538a707 100644
--- a/custom/c_help.c
+++ b/custom/c_help.c
@@ -1,7 +1,7 @@
 /*
  * c_help - custom help function
  *
- * Copyright (C) 1999-2004,2021,2022  Landon Curt Noll
+ * Copyright (C) 1999-2004,2021-2023  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
@@ -32,7 +32,7 @@
 #if defined(CUSTOM)
 int c_help_allowed = 1;		/* CUSTOM defined */
 #else /* CUSTOM */
-int c_help_allowed = 0;		/* CUSTOM defined */
+int c_help_allowed = 0;		/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_pmodm127.c b/custom/c_pmodm127.c
index 6ea19f1..5201f95 100644
--- a/custom/c_pmodm127.c
+++ b/custom/c_pmodm127.c
@@ -1,7 +1,7 @@
 /*
  * c_pmodm127 - calculate q mod 2^(2^127-1)
  *
- * Copyright (C) 2004-2007,2021,2022  Landon Curt Noll
+ * Copyright (C) 2004-2007,2021-2023  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
@@ -31,7 +31,7 @@
 #if defined(CUSTOM)
 int c_pmodm127_allowed = 1;	/* CUSTOM defined */
 #else /* CUSTOM */
-int c_pmodm127_allowed = 0;	/* CUSTOM defined */
+int c_pmodm127_allowed = 0;	/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_pzasusb8.c b/custom/c_pzasusb8.c
index 4b50503..7db143e 100644
--- a/custom/c_pzasusb8.c
+++ b/custom/c_pzasusb8.c
@@ -1,7 +1,7 @@
 /*
  * c_pzasusb8 - print numerator as a string of USB8s
  *
- * Copyright (C) 1999-2004,2021,2022  Ernest Bowen
+ * Copyright (C) 1999-2004,2021-2023  Ernest Bowen
  *
  * 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
@@ -31,7 +31,7 @@
 #if defined(CUSTOM)
 int c_pzasusb8_allowed = 1;	/* CUSTOM defined */
 #else /* CUSTOM */
-int c_pzasusb8_allowed = 0;	/* CUSTOM defined */
+int c_pzasusb8_allowed = 0;	/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_register.c b/custom/c_register.c
index f841fa4..72553c3 100644
--- a/custom/c_register.c
+++ b/custom/c_register.c
@@ -1,7 +1,7 @@
 /*
  * c_register - set or print a custom register value
  *
- * Copyright (C) 2007,2021,2022  Landon Curt Noll
+ * Copyright (C) 2007,2021-2023  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
@@ -32,7 +32,7 @@
 #if defined(CUSTOM)
 int c_register_allowed = 1;	/* CUSTOM defined */
 #else /* CUSTOM */
-int c_register_allowed = 0;	/* CUSTOM defined */
+int c_register_allowed = 0;	/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/c_sysinfo.c b/custom/c_sysinfo.c
index 2cbf4e6..cefbeb3 100644
--- a/custom/c_sysinfo.c
+++ b/custom/c_sysinfo.c
@@ -1,7 +1,7 @@
 /*
  * c_sysinfo - names and values of selected #defines
  *
- * Copyright (C) 1999-2007,2021,2022  Landon Curt Noll
+ * Copyright (C) 1999-2007,2021-2023  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
@@ -32,7 +32,7 @@
 #if defined(CUSTOM)
 int c_sysinfo_allowed = 1;	/* CUSTOM defined */
 #else /* CUSTOM */
-int c_sysinfo_allowed = 0;	/* CUSTOM defined */
+int c_sysinfo_allowed = 0;	/* CUSTOM undefined */
 #endif /* CUSTOM */
 
 
diff --git a/custom/custtbl.c b/custom/custtbl.c
index f312a22..71c6b25 100644
--- a/custom/custtbl.c
+++ b/custom/custtbl.c
@@ -1,7 +1,7 @@
 /*
  * custtbl - custom interface table
  *
- * Copyright (C) 1999-2007,2021  Landon Curt Noll
+ * Copyright (C) 1999-2007,2021,2023  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
@@ -24,6 +24,18 @@
  * Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/
  */
 
+
+/*
+ * ISO C requires a translation unit to contain at least one declaration,
+ * so we declare a global variable whose value is based on if CUSTOM is defined.
+ */
+#if defined(CUSTOM)
+int custtbl_allowed = 1;	/* CUSTOM defined */
+#else /* CUSTOM */
+int custtbl_allowed = 0;	/* CUSTOM undefined */
+#endif /* CUSTOM */
+
+
 #include <unistd.h>
 
 #include "../have_const.h"
@@ -35,8 +47,7 @@
 
 
 /*
- * NOTE: See the file CUSTOM for instructions on how to add
- *	 custom functions.
+ * NOTE: See the file HOW_TO_ADD for instructions on how to add custom functions.
  */