--- a/configure.ac
+++ b/configure.ac
@@ -95,6 +95,8 @@ AC_SUBST(LIBUNBOUND_CURRENT)
 AC_SUBST(LIBUNBOUND_REVISION)
 AC_SUBST(LIBUNBOUND_AGE)
 
+PKG_PROG_PKG_CONFIG
+
 CFLAGS="$CFLAGS"
 AC_AIX
 if test "$ac_cv_header_minix_config_h" = "yes"; then