diff --git a/CHANGES b/CHANGES
index 7d66962..e07e5b8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -15,32 +15,53 @@ The following are the changes from calc version 2.12.7.1 to date:
 	    \t	tab		byte 0x09 in ASCII encoding
 	    \v	vertical tab	byte 0x0b in ASCII encoding
 
-     Fixed a segfault when getpwuid() returned NULL during initialization.
-     Thanks goes to baratharon GitHub user for reporting this issue.
+    Fixed a segfault when getpwuid() returned NULL during initialization.
+    Thanks goes to baratharon GitHub user for reporting this issue.
 
-     Requiring calc shell scripts to use -s -f at the end of the
-     initial #! line.
+    Requiring calc shell scripts to use -s -f at the end of the
+    initial #! line.
 
-     Fixed /tmp/mersenne example in calc(1) man page.
+    Fixed /tmp/mersenne example in calc(1) man page.
 
-     Added make variable ${ARCH_CFLAGS}.  The ${ARCH_CFLAGS} is
-     added after ${CCMISC} and before ${EXTRA_CFLAGS} when building
-     the ${CFLAGS} for compiling C code.  are ${CC} when compiling
-     C files.  The default value is:
+    Added make variable ${ARCH_CFLAGS}.  The ${ARCH_CFLAGS} is
+    added after ${CCMISC} and before ${EXTRA_CFLAGS} when building
+    the ${CFLAGS} for compiling C code.  are ${CC} when compiling
+    C files.  The default value is:
 
 	ARCH_CFLAGS= -march=native
 
-     which directs C compiler to compile for the native machine.
-     To disable use of '-march=native', set ARCH_CFLAGS to the empty
-     string as in:
+    which directs C compiler to compile for the native machine.
+    To disable use of '-march=native', set ARCH_CFLAGS to the empty
+    string as in:
 
 	make all ARCH_CFLAGS=
 
-     To make calc RPMs more portable, they are compiled with an
-     empty ARCH_CFLAGS.
+    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.
+    Fixed issues relating to compiling on macOS.  Fixed issues
+    where <unistd.h> is needed.
+
+    Fixed typos in help/intro and README.md. <<GitHub guilhermgonzaga>>
+
+    Copied missing description lines from help/intro to README.md
+    "What is calc?" section.  <<GitHub guilhermgonzaga>>
+
+    GCC 7 added a warning on fall throughs in case statements.  It's
+    enabled by -Wextra and treated as an error due to -Wall so it
+    breaks compilation.  See -Wimplicit-fallthrough in the GCC
+    manual.  The default value is 3, which means a comment matching
+    some specific regexes is enough to disable the warning.
+    Fixed spaces vs tabs and use FALLTHRU as it's used elsewhere.
+    Fixed one FALLTHRU comment that was inconsistent with others.
+    <<thanks jcul>>
+
+    Fixed minor typo on help/power. <<GitHub thegithubr>>
+
+    By default, the calc history file is located in ~/.calc_history.
+    Now, if the environment variable $CALCHISTFILE is defined
+    and is non-empty, then calc history file will be defined
+    by the $CALCHISTFILE environment variable.
 
 
 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 3689b5d..9c8cd96 100644
--- a/Makefile.ship
+++ b/Makefile.ship
@@ -1054,7 +1054,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.4
+VERSION= 2.12.7.5
 
 # Names of shared libraries with versions
 #
@@ -5475,6 +5475,7 @@ hist.o: have_unistd.h
 hist.o: have_unused.h
 hist.o: hist.c
 hist.o: hist.h
+hist.o: lib_calc.h
 hist.o: longbits.h
 hist.o: nametype.h
 hist.o: qmath.h
diff --git a/calc.h b/calc.h
index 3165f13..180b464 100644
--- a/calc.h
+++ b/calc.h
@@ -48,6 +48,7 @@
 #define HOME		"HOME"		/* environment variable for home dir */
 #define PAGER		"PAGER"		/* environment variable for help */
 #define SHELL		"SHELL"		/* environment variable for shell */
+#define CALCHISTFILE	"CALCHISTFILE"	/* history file environment variable */
 #define DEFAULTCALCBINDINGS "bindings"	/* default calc bindings file */
 #define DEFAULTCALCHELP "help"		/* help file that -h prints */
 #define DEFAULTSHELL	"sh"		/* default shell to use */
diff --git a/calc.man b/calc.man
index 25602a2..db57279 100644
--- a/calc.man
+++ b/calc.man
@@ -1103,6 +1103,14 @@ Default value: binding
 This variable is not used if calc was compiled with GNU-readline support.
 In that case, the standard readline mechanisms (see readline(3)) are used.
 .sp
+.TP 5
+CALCHISTFILE
+Location of the calc history file.
+.sp
+Default value: ~/.calc_history
+.sp
+This variable is not used if calc was compiled with GNU-readline support.
+.sp
 .SH CREDIT
 \&
 .br
diff --git a/custom/Makefile b/custom/Makefile
index 2de4ecc..6b86fb3 100644
--- a/custom/Makefile
+++ b/custom/Makefile
@@ -348,7 +348,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.4
+VERSION= 2.12.7.5
 
 # Names of shared libraries with versions
 #
diff --git a/custom/Makefile.head b/custom/Makefile.head
index 1dff4be..2c8fce9 100644
--- a/custom/Makefile.head
+++ b/custom/Makefile.head
@@ -348,7 +348,7 @@ EXT=
 
 # The default calc versions
 #
-VERSION= 2.12.7.4
+VERSION= 2.12.7.5
 
 # Names of shared libraries with versions
 #
diff --git a/help/environment b/help/environment
index 41d458d..e414988 100644
--- a/help/environment
+++ b/help/environment
@@ -7,7 +7,8 @@ Environment variables
 
 		/	./	../	~
 
-	If this variable does not exist, a compiled value
+	If this variable does not exist, or if this
+	variable is an empty string, a compiled value
 	is used.  Typically compiled in value is:
 
 		    .:./cal:~/cal:${CALC_SHAREDIR}:${CUSTOMCALDIR}
@@ -27,7 +28,8 @@ Environment variables
 	line), calc searches for files along the :-separated
 	$CALCRC environment variable.
 
-	If this variable does not exist, a compiled value
+	If this variable does not exist, or if this
+        variable is an empty string, a compiled value
 	is used.  Typically compiled in value is:
 
 		    ${CALC_SHAREDIR}/startup:~/.calcrc:./.calcinit
@@ -66,7 +68,8 @@ Environment variables
 	This value is taken to be the home directory of the
 	current user.  It is used when files begin with '~/'.
 
-	If this variable does not exist, the home directory password
+	If this variable does not exist, or if this
+	variable is an empty string, the home directory password
 	entry of the current user is used.  If that information
 	is not available, '.' is used.
 
@@ -75,7 +78,8 @@ Environment variables
 	When invoking help, this environment variable is used
 	to display a help file.
 
-	If this variable does not exist, a compiled value
+	If this variable does not exist, or if this
+	variable is an empty string, a compiled value
 	is used.  Typically compiled in value is something
 	such as 'more', 'less', 'pg' or 'cat'.
 
@@ -84,11 +88,20 @@ Environment variables
 	When a !-command is used, the program indicated by
 	this environment variable is used.
 
-	If this variable does not exist, a compiled value
+	If this variable does not exist, or if this
+	variable is an empty string, a compiled value
 	is used.  Typically compiled in value is something
 	such as 'sh' is used.
 
-## Copyright (C) 1999  Landon Curt Noll
+    CALCHISTFILE
+
+	This value is taken to be the calc history file.
+
+	If this variable does not exist, or if this
+	variable is an empty string, then ~/.calc_history
+	is used.
+
+## 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
diff --git a/hist.c b/hist.c
index 8c74058..d5df1d3 100644
--- a/hist.c
+++ b/hist.c
@@ -51,6 +51,7 @@
 #endif
 
 #include "calc.h"
+#include "lib_calc.h"
 #include "hist.h"
 #include "have_string.h"
 
@@ -1461,9 +1462,6 @@ quit_calc(void)
  */
 
 
-/* name of history file */
-char *my_calc_history = NULL;
-
 size_t
 hist_getline(char *prompt, char *buf, size_t len)
 {
@@ -1504,8 +1502,8 @@ my_stifle_history (void)
 	/* only save last number of entries */
 	stifle_history(HISTORY_LEN);
 
-	if (my_calc_history)
-		write_history(my_calc_history);
+	if (calc_history)
+		write_history(calc_history);
 }
 
 
@@ -1519,10 +1517,12 @@ hist_init(char UNUSED *filename)
 	using_history();
 
 	/* name of history file */
-	my_calc_history = tilde_expand("~/.calc_history");
+	if (calc_history == NULL) {
+		calc_history = tilde_expand("~/.calc_history");
+	}
 
 	/* read previous history */
-	read_history(my_calc_history);
+	read_history(calc_history);
 
 	atexit(my_stifle_history);
 
diff --git a/lib_calc.c b/lib_calc.c
index d5ffd1e..c18285c 100644
--- a/lib_calc.c
+++ b/lib_calc.c
@@ -145,6 +145,7 @@ char *calcbindings = NULL;	/* $CALCBINDINGS or default */
 char *home = NULL;		/* $HOME or default */
 char *pager = NULL;		/* $PAGER or default */
 char *shell = NULL;		/* $SHELL or default */
+char *calc_history = NULL;	/* $CALCHISTFILE or ~/.calc_history */
 int stdin_tty = FALSE;		/* TRUE if stdin is a tty */
 int havecommands = FALSE;	/* TRUE if have one or more cmd args */
 long stoponerror = 0;		/* >0 => stop, <0 => continue, ==0 => use -c */
@@ -546,6 +547,12 @@ initenv(void)
 	shell = (c ? strdup(c) : NULL);
 	if (shell == NULL || *shell == '\0')
 		shell = DEFAULTSHELL;
+
+	/* determine the $CALCHISTFILE value */
+	c = (no_env ? NULL : getenv(CALCHISTFILE));
+	calc_history = (c ? strdup(c) : NULL);
+	if (calc_history == NULL || *calc_history == '\0')
+		calc_history = NULL;	/* will use ~/.calc_history */
 }
 
 
diff --git a/lib_calc.h b/lib_calc.h
index 8c4a44d..2a510c4 100644
--- a/lib_calc.h
+++ b/lib_calc.h
@@ -74,4 +74,9 @@ EXTERN int calc_print_scanwarn_msg;
 /* number of parse/scan warnings found */
 EXTERN unsigned long calc_warn_cnt;
 
+/*
+ * calc history file
+ */
+EXTERN char *calc_history;
+
 #endif /* !INCLUDE_MATH_ERROR_H */
diff --git a/version.c b/version.c
index 44ca543..1ec46fe 100644
--- a/version.c
+++ b/version.c
@@ -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	4	/* minor software level or 0 if not patched */
+#define MINOR_PATCH	5	/* minor software level or 0 if not patched */
 
 
 /*