diff --git a/bootstrap.sh b/bootstrap.sh
index 1a161c8..52ecda4 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -40,7 +40,7 @@
 
 # we require automake 1.13 or later
 # check must happen externally due to use of newer macro
-AUTOMAKE_VERSION=`automake --version | head -n1 | rev | sed -e 's/\s.*$//' | rev`
+AUTOMAKE_VERSION=`automake --version | grep automake | egrep -o '([0-9]{1,}\.)+[0-9]{1,}'`
 if [ "$AUTOMAKE_VERSION" \< "1.13" ]; then
   echo >&2 "automake version $AUTOMAKE_VERSION is too old (need 1.13 or later)"
   exit 1