diff --git a/libcharset/m4/libtool.m4 b/libcharset/m4/libtool.m4
index 39ba996..69ca81f 100644
--- a/libcharset/m4/libtool.m4
+++ b/libcharset/m4/libtool.m4
@@ -89,7 +89,7 @@
 LIBTOOL_DEPS="$ltmain"
 
 # Always use our own libtool.
-LIBTOOL='$(SHELL) $(top_builddir)/libtool'
+LIBTOOL="${CONFIG_SHELL-$SHELL} "'$(top_builddir)/libtool'
 AC_SUBST(LIBTOOL)dnl
 
 _LT_SETUP