--- ./aclocal.m4
+++ ./aclocal.m4
@@ -12,7 +12,7 @@
 cat > conftest.$ac_ext <<EOF
 [#]line __oline__ "configure"
 #include "confdefs.h"
-ifelse(AC_LANG, CPLUSPLUS, [#ifdef __cplusplus
+AC_LANG_CASE([C++], [#ifdef __cplusplus
 extern "C" void exit(int);
 #endif
 ])dnl
--- ./configure.in
+++ ./configure.in
@@ -127,6 +127,7 @@
 AC_CACHE_VAL(blt_cv_prog_cc, blt_cv_prog_cc=$CC)
 AC_SUBST(CC)
 AC_PROG_CPP
+AC_PROG_EGREP
 if test "x${GCC}" != "x" ; then
   blt_have_gcc="yes"
 else