diff --git a/configure.ac b/configure.ac
index d4fa3df2f0750502be2f81da8856ecb1fd4cdd20..d5a793e46660546b284133d9161e36b4bfc8f5c9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,8 +40,7 @@ AC_PROG_LIBTOOL
 LT_INIT
 
 # Use pkg-config
-PKG_PROG_PKG_CONFIG
-PKG_INSTALLDIR
+m4_ifdef([PKG_INSTALLDIR], [PKG_INSTALLDIR], [AC_SUBST([pkgconfigdir], ['${libdir}/pkgconfig'])])
 AC_CONFIG_FILES([libknot.pc])
 
 AC_CACHE_CHECK([for reentrant lex], [ac_cv_path_LEX],