diff --git a/classes/autoconf.yaml b/classes/autoconf.yaml
index ecfc1c29..53918a9a 100644
--- a/classes/autoconf.yaml
+++ b/classes/autoconf.yaml
@@ -56,31 +56,36 @@ buildSetup: |
 
         if [[ ( ! -e configure ) || ( ! -e .autoreconf.stamp ) ||
               ( configure.ac -nt .autoreconf.stamp ) ]] ; then
-            (
-                # Work around a stupid perl limitation that does not retain
-                # sub-second file timestamps when moving files across file
-                # system boundaries. Make sure rename() always works.
-                # Otherwise files may appear older than they are and trigger
-                # reconfigurations in the build step.
-                export TMPDIR="$BOB_CWD"
+            ${AUTOCONF_BOOTSTRAP_TOOL:-}
+            if [[ -n ${AUTOCONF_TOOL:-} ]]; then
+                ${AUTOCONF_TOOL}
+            else
+                (
+                    # Work around a stupid perl limitation that does not retain
+                    # sub-second file timestamps when moving files across file
+                    # system boundaries. Make sure rename() always works.
+                    # Otherwise files may appear older than they are and trigger
+                    # reconfigurations in the build step.
+                    export TMPDIR="$BOB_CWD"
 
-                # We don't want to retain any backups. Give them a unique
-                # suffix so that they can be garbage collected.
-                export SIMPLE_BACKUP_SUFFIX=.bob-backup
+                    # We don't want to retain any backups. Give them a unique
+                    # suffix so that they can be garbage collected.
+                    export SIMPLE_BACKUP_SUFFIX=.bob-backup
 
-                # Autoreconf will not replace existing autoconf-archive macros
-                # in the m4 directory. If that is needed, the recipe must
-                # force the update.
-                if [[ $CALL_ACLOCAL ]] ; then
-                    if [[ -n "${ACLOCAL_ARGS[@]:+set}" ]] ; then
-                        aclocal "${ACLOCAL_ARGS[@]}"
-                    else
-                        aclocal -I m4 --install
+                    # Autoreconf will not replace existing autoconf-archive macros
+                    # in the m4 directory. If that is needed, the recipe must
+                    # force the update.
+                    if [[ $CALL_ACLOCAL ]] ; then
+                        if [[ -n "${ACLOCAL_ARGS[@]:+set}" ]] ; then
+                            aclocal "${ACLOCAL_ARGS[@]}"
+                        else
+                            aclocal -I m4 --install
+                        fi
                     fi
-                fi
-                autoreconf -v ${AUTORECONF_FORCE:+-fi} \
-                    ${AUTOCONF_EXTRA_PKGS[@]+"${AUTOCONF_EXTRA_PKGS[@]/#/-I}"}
-            )
+                    autoreconf -v ${AUTORECONF_FORCE:+-fi} \
+                        ${AUTOCONF_EXTRA_PKGS[@]+"${AUTOCONF_EXTRA_PKGS[@]/#/-I}"}
+                )
+            fi
             rm -rf autom4te.cache
             find . -name '*.bob-backup' -delete
             touch .autoreconf.stamp