--- ../calc-2.14.0.14/Makefile	2021-12-28 03:09:44.000000000 +0000
+++ ./Makefile	2022-02-06 20:21:21.491282701 +0000
@@ -136,7 +136,7 @@
 #
 #	PREFIX= /usr/local
 #
-PREFIX= /usr/local
+PREFIX ?= /usr/local
 #PREFIX= /usr
 #PREFIX= /usr/global
 
@@ -261,7 +261,7 @@
 #
 # Select LONG_BITS= 32 for DJGPP.
 #
-LONG_BITS=
+#LONG_BITS=
 #LONG_BITS= 32
 #LONG_BITS= 64
 
@@ -779,8 +779,8 @@
 #endif	/* end of skip for non-Gnu makefiles */
 
 # default INCDIR for non-macOS
-INCDIR= /usr/include
-#INCDIR= ${PREFIX}/include
+#INCDIR= /usr/include
+INCDIR= ${PREFIX}/include
 #INCDIR= /dev/env/DJDIR/include
 
 #if 0	/* start of skip for non-Gnu makefiles */
@@ -846,8 +846,8 @@
 #endif	/* end of skip for non-Gnu makefiles */
 
 # default BINDIR for non-macOS
-BINDIR= /usr/bin
-#BINDIR= ${PREFIX}/bin
+#BINDIR= /usr/bin
+BINDIR= ${PREFIX}/bin
 #BINDIR= /dev/env/DJDIR/bin
 
 #if 0	/* start of skip for non-Gnu makefiles */
@@ -864,8 +864,8 @@
 #endif	/* end of skip for non-Gnu makefiles */
 
 # default LIBDIR for non-macOS
-LIBDIR= /usr/lib
-#LIBDIR= ${PREFIX}/lib
+#LIBDIR= /usr/lib
+LIBDIR= ${PREFIX}/lib
 #LIBDIR= /dev/env/DJDIR/lib
 
 #if 0	/* start of skip for non-Gnu makefiles */
@@ -882,8 +882,8 @@
 #endif	/* end of skip for non-Gnu makefiles */
 
 # default CALC_SHAREDIR for non-macOS
-CALC_SHAREDIR= /usr/share/calc
-#CALC_SHAREDIR= ${PREFIX}/lib/calc
+#CALC_SHAREDIR= /usr/share/calc
+CALC_SHAREDIR= ${PREFIX}/lib/calc
 #CALC_SHAREDIR= /dev/env/DJDIR/share/calc
 
 #if 0	/* start of skip for non-Gnu makefiles */
@@ -925,7 +925,7 @@
 CUSTOMCALDIR= ${CALC_SHAREDIR}/custom
 CUSTOMHELPDIR= ${CALC_SHAREDIR}/custhelp
 CUSTOMINCDIR= ${CALC_INCDIR}/custom
-SCRIPTDIR= ${BINDIR}/cscript
+SCRIPTDIR= ${CALC_SHAREDIR}/cscript
 
 # T - top level directory under which calc will be installed
 #
@@ -967,7 +967,7 @@
 #
 # If in doubt, use T=
 #
-T=
+T=${DESTDIR}
 
 # where man section 1 pages are installed
 #
@@ -991,7 +991,7 @@
 else
 #
 #endif	/* end of skip for non-Gnu makefiles */
-MANDIR= /usr/share/man/man1
+MANDIR= ${PREFIX}/share/man/man1
 #if 0	/* start of skip for non-Gnu makefiles */
 #
 endif
@@ -1144,14 +1144,14 @@
 #READLINE_LIB=
 #READLINE_EXTRAS=
 #
-READLINE_LIB= -lreadline
-READLINE_EXTRAS= -lhistory -lncurses
+#READLINE_LIB= -lreadline
+#READLINE_EXTRAS= -lhistory -lncurses
 #
 #READLINE_LIB= -L/usr/gnu/lib -lreadline
 #READLINE_EXTRAS= -lhistory -lncurses
 #
-#READLINE_LIB= -L${PREFIX}/lib -lreadline
-#READLINE_EXTRAS= -lhistory -lncurses
+READLINE_LIB= -L${PREFIX}/lib -lreadline
+READLINE_EXTRAS= -lhistory -lncurses
 #
 # For Apple OS X: install fink from http://fink.sourceforge.net
 #		  and then do a 'fink install readline' and then use:
@@ -1168,9 +1168,9 @@
 #READLINE_LIB= -L${PREFIX}/opt/readline/lib -lreadline
 #READLINE_EXTRAS= -lhistory -lncurses
 #
-READLINE_INCLUDE=
+#READLINE_INCLUDE=
 #READLINE_INCLUDE= -I/usr/gnu/include
-#READLINE_INCLUDE= -I${PREFIX}/include
+READLINE_INCLUDE= -I${PREFIX}/include
 
 #if 0   /* start of skip for non-Gnu makefiles */
 #
@@ -1227,7 +1227,7 @@
 # a *.a link library.  Set RANLIB to the utility that performs this
 # action.  Set RANLIB to : if your system does not need such a utility.
 #
-RANLIB=ranlib
+RANLIB?=ranlib
 #RANLIB=:
 
 # Normally certain files depend on the Makefile.  If the Makefile is
@@ -1306,7 +1306,7 @@
 
 # standard utilities used during make
 #
-AR= ar
+AR?= ar
 AWK= awk
 CAT= cat
 CHMOD= chmod
@@ -1508,7 +1508,7 @@
 BLD_TYPE= calc-dynamic-only
 #
 CC_SHARE= -fPIC
-DEFAULT_LIB_INSTALL_PATH= ${PWD}:/lib:/usr/lib:${LIBDIR}:${PREFIX}/lib
+DEFAULT_LIB_INSTALL_PATH= ${PWD}:${LIBDIR}:${PREFIX}/lib
 LD_SHARE= "-Wl,-rpath,${DEFAULT_LIB_INSTALL_PATH}" \
     "-Wl,-rpath-link,${DEFAULT_LIB_INSTALL_PATH}"
 LIBCALC_SHLIB= -shared "-Wl,-soname,libcalc${LIB_EXT_VERSION}"
@@ -1548,7 +1548,7 @@
 CCMISC=
 #
 LCC= gcc
-CC= ${PURIFY} ${LCC} ${CCWERR}
+CC?= ${PURIFY} ${LCC} ${CCWERR}
 #
 endif