--- a/configure.ac
+++ b/configure.ac
@@ -5,7 +5,7 @@
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_LIBOBJ_DIR([lib])
 AC_CONFIG_SRCDIR([src/ftpclass.cc])
-AM_CONFIG_HEADER([lib/config.h])
+AC_CONFIG_HEADERS([lib/config.h])
 AM_INIT_AUTOMAKE
 
 dnl This doesn't *require* GNU extensions; it merely enables them if
