diff -Naur a/configure b/configure
--- a/configure	2020-11-01 13:53:55.000000000 +0000
+++ b/configure	2021-04-28 19:34:29.246125644 +0000
@@ -20654,7 +20654,7 @@
   HAVE_CXX11_FALSE=
 fi
 
- if test "x$with_int" == "ximath-32"; then
+ if test "x$with_int" = "ximath-32"; then
   SMALL_INT_OPT_TRUE=
   SMALL_INT_OPT_FALSE='#'
 else
@@ -20662,7 +20662,7 @@
   SMALL_INT_OPT_FALSE=
 fi
 
-if test "x$with_int" == "ximath-32"; then :
+if test "x$with_int" = "ximath-32"; then :
 
 
 $as_echo "#define USE_SMALL_INT_OPT /**/" >>confdefs.h
diff -Naur a/configure.ac b/configure.ac
--- a/configure.ac	2020-11-01 13:53:47.000000000 +0000
+++ b/configure.ac	2021-04-28 19:34:28.615119537 +0000
@@ -83,8 +83,8 @@
 AM_CONDITIONAL(GMP_FOR_MP, test x$with_int = xgmp)
 
 AM_CONDITIONAL(HAVE_CXX11, test "x$HAVE_CXX11" = "x1")
-AM_CONDITIONAL(SMALL_INT_OPT, test "x$with_int" == "ximath-32")
-AS_IF([test "x$with_int" == "ximath-32"], [
+AM_CONDITIONAL(SMALL_INT_OPT, test "x$with_int" = "ximath-32")
+AS_IF([test "x$with_int" = "ximath-32"], [
 	AC_DEFINE([USE_SMALL_INT_OPT], [], [Use small integer optimization])
 ])