diff --git a/m4/ax_prog_perl_version.m4 b/m4/ax_prog_perl_version.m4
index 18d9f74..d794c1a 100644
--- a/m4/ax_prog_perl_version.m4
+++ b/m4/ax_prog_perl_version.m4
@@ -35,7 +35,7 @@
# and this notice are preserved. This file is offered as-is, without any
# warranty.
-#serial 11
+#serial 12
AC_DEFUN([AX_PROG_PERL_VERSION],[
AC_REQUIRE([AC_PROG_SED])
@@ -46,7 +46,11 @@
AC_MSG_CHECKING([for perl version])
changequote(<<,>>)
- perl_version=`$PERL --version 2>&1 | $GREP "This is perl" | $SED -e 's/.* v\([0-9]*\.[0-9]*\.[0-9]*\) .*/\1/'`
+ perl_version=`$PERL --version 2>&1 \
+ | $SED -n -e '/This is perl/b inspect
+b
+: inspect
+s/.* (\{0,1\}v\([0-9]*\.[0-9]*\.[0-9]*\))\{0,1\} .*/\1/;p'`
changequote([,])
AC_MSG_RESULT($perl_version)