--- a/Makefile.am	Mon Mar 07 19:07:25 2016 -0500
+++ b/Makefile.am	Mon Mar 07 19:06:35 2016 -0500
@@ -46,6 +46,7 @@
   NEWS \
   README \
   build-aux/OctJavaQry.class \
+  build-aux/check-subst-vars.in.sh \
   build-aux/find-files-with-tests.sh \
   build-aux/mk-default-qt-settings.in.sh \
   build-aux/mk-f77-def.in.sh \
@@ -63,6 +64,25 @@
   run-octave.in \
   $(BUILT_DISTFILES)
 
+GEN_CONFIG_SHELL = \
+  build-aux/mk-default-qt-settings.sh \
+  build-aux/mk-f77-def.sh \
+  build-aux/mk-mxarray-h.sh \
+  build-aux/mk-version-h.sh \
+  build-aux/subst-config-vals.sh \
+  build-aux/subst-cross-config-vals.sh \
+  build-aux/subst-default-vals.sh \
+  build-aux/subst-f77-isnan-macro.sh \
+  build-aux/subst-script-vals.sh
+
+AUTOCONF_SUBST_VARS = @AUTOCONF_SUBST_VARS@
+ALL_SUBST_VARS = \
+  $(AUTOCONF_SUBST_VARS) \
+  abs_top_builddir \
+  abs_top_srcdir \
+  api_version \
+  version
+
 DIRSTAMP_FILES =
 
 octave_dirstamp = $(am__leading_dot)octave-dirstamp
@@ -173,7 +193,9 @@
 noinst_SCRIPTS = run-octave
 
 CLEANFILES += \
-  $(BUILT_SOURCES)
+  $(BUILT_SOURCES) \
+  config-vars \
+  make-vars
 
 DISTCLEANFILES += \
   .gdbinit \
@@ -214,6 +236,23 @@
 	$(AM_V_GEN)$(MKDIR_P) bits && \
 	$(INSTALL_HEADER) $< $@
 
+config-vars: $(GEN_CONFIG_SHELL)
+	$(AM_V_GEN)rm -f $@-t $@ && \
+	$(SED) -n 's/  *"$$/"/; s/^\([A-Za-z_][A-Za-z0-9_]*\)=" *\(.*\)" *$$/\1 \2/p' $^ | sort -u > $@-t && \
+	mv $@-t $@
+
+## We always have to create this file because values for Make variables
+## may be passed on the command line.
+
+make-vars:
+	$(file >$@-t) $(foreach v, $(ALL_SUBST_VARS), $(file >>$@-t,$(v) $(value $(v))))
+	$(AM_V_GEN)mv $@-t $@
+.PHONY: make-vars
+
+check-subst-vars: build-aux/check-subst-vars.sh make-vars config-vars
+	@$(SHELL) -f build-aux/check-subst-vars.sh make-vars config-vars
+.PHONY: check-subst-vars
+
 ## If we aren't trying to fix stl_algo.h, then try to ensure that
 ## there isn't a stray copy sitting in the build tree.
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/build-aux/check-subst-vars.in.sh	Mon Mar 07 19:06:35 2016 -0500
@@ -0,0 +1,68 @@
+#! /bin/sh
+#
+# Copyright (C) 2016 John W. Eaton
+#
+# This file is part of Octave.
+#
+# Octave is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or (at
+# your option) any later version.
+#
+# Octave is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Octave; see the file COPYING.  If not, see
+# <http://www.gnu.org/licenses/>.
+
+: ${AWK=@AWK@}
+: ${SED=@SED@}
+
+if test $# -ne 2; then
+  echo "usage: check-subst-vars.sh make-vars-file config-vars-file" 2>&1
+  exit 1
+fi
+
+awk_script="check-subst-vars-$$.awk"
+
+trap "rm -f $awk_script; exit 1" 1 2 15
+
+make_vars="$1"
+config_vars="$2"
+
+## Generate awk script to check variable consitency.
+
+cat << EOF > $awk_script
+BEGIN {
+  status = 0;
+EOF
+
+while read var val; do
+  val=`echo "$val" | $SED 's/"/\\\\"/g'`
+  echo "make_vars[\"$var\"] = \"$val\";" >> $awk_script
+done < $make_vars
+
+cat << EOF >> $awk_script
+} {
+  line = \$0;
+  idx = index (line, " ");
+  var = substr (line, 1, idx-1);
+  val = substr (line, idx+1);
+  if (val != make_vars[var])
+    {
+      printf ("error: mismatch for configuration variable '%s'\n", var);
+      printf ("  value set in configuration files: %s\n", val);
+      printf ("  value set in Make: %s\n", make_vars[var]);
+      status = 1;
+    }
+} END {
+  exit status;
+}
+EOF
+
+## Execute it.
+
+$AWK -f $awk_script $config_vars 1>&2

--- a/build-aux/common.mk	Mon Mar 07 19:07:25 2016 -0500
+++ b/build-aux/common.mk	Mon Mar 07 19:06:35 2016 -0500
@@ -5,8 +5,8 @@
 export SHELL
 export PERL
 
-version = ${OCTAVE_VERSION}
-api_version = ${OCTAVE_API_VERSION}
+version := ${OCTAVE_VERSION}
+api_version := ${OCTAVE_API_VERSION}
 
 ## AM_LIBTOOLFLAGS = --silent
 

--- a/configure.ac	Mon Mar 07 19:07:25 2016 -0500
+++ b/configure.ac	Mon Mar 07 19:06:35 2016 -0500
@@ -3378,11 +3378,15 @@
 ### Do the substitutions in Makefiles and other scripts that
 ### hold configuration info.
 
+AUTOCONF_SUBST_VARS="`echo $ac_subst_vars`"
+
+AC_SUBST(AUTOCONF_SUBST_VARS)
 AC_SUBST(ac_config_files)
 AC_SUBST(ac_config_headers)
 
 AC_CONFIG_FILES([
   Makefile
+  build-aux/check-subst-vars.sh:build-aux/check-subst-vars.in.sh
   doc/doxyhtml/Doxyfile
   libgnu/Makefile])
 
@@ -3395,15 +3399,15 @@
   [$SHELL $srcdir/build-aux/move-if-change oct-conf-post.h-tmp oct-conf-post.h])
 
 OCTAVE_CONFIG_MOVE_IF_CHANGE_FILES([
+  build-aux/mk-default-qt-settings.sh
+  build-aux/mk-f77-def.sh
   build-aux/mk-mxarray-h.sh
   build-aux/mk-version-h.sh
   build-aux/subst-config-vals.sh
   build-aux/subst-cross-config-vals.sh
   build-aux/subst-default-vals.sh
   build-aux/subst-f77-isnan-macro.sh
-  build-aux/subst-script-vals.sh
-  build-aux/mk-default-qt-settings.sh
-  build-aux/mk-f77-def.sh])
+  build-aux/subst-script-vals.sh])
 
 AC_OUTPUT