--- a/configure.ac
+++ b/configure.ac
@@ -25,32 +25,40 @@
 AC_PROG_YACC
 AC_SUBST(YACC)
 
+PKG_PROG_PKG_CONFIG([0.24])
+
 # Checks for libraries.
-pkg_modules="gtk+-2.0 >= 2.0.0"
-PKG_CHECK_MODULES(GTK, [$pkg_modules])
+PKG_CHECK_MODULES(GTK, [gtk+-2.0 >= 2.0.0])
 AC_SUBST(GTK_CFLAGS)
 AC_SUBST(GTK_LIBS)
 
-pkg_modules="gthread-2.0"
-PKG_CHECK_MODULES(GTHREAD, [$pkg_modules])
+PKG_CHECK_MODULES(GTHREAD, [gthread-2.0])
 AC_SUBST(GTHREAD_CFLAGS)
 AC_SUBST(GTHREAD_LIBS)
 
-glade_lib="libglade-2.0"
-PKG_CHECK_MODULES([GLADE_LIB], \
-	[$glade_lib], \
-	AC_SUBST(HAVE_GLADE_LIB, 1),\
-	AC_SUBST(HAVE_GLADE_LIB, 0))
-AC_SUBST(GLADE_LIB_CFLAGS)
-AC_SUBST(GLADE_LIB_LIBS)
-
-vte_lib="vte >= 0.23.5"
-PKG_CHECK_MODULES([VTE], \
-	[$vte_lib], \
-	AC_SUBST(HAVE_VTE, 1),\
-	AC_SUBST(HAVE_VTE, 0))
-AC_SUBST(VTE_CFLAGS)
-AC_SUBST(VTE_LIBS)
+AC_ARG_WITH([glade],
+  AS_HELP_STRING([--with-glade], [enable support for libglade])
+)
+
+AC_ARG_WITH([vte],
+  AS_HELP_STRING([--with-vte], [enable support for vte])
+)
+
+AS_IF(
+  [test "x$with_glade" = "xyes"],
+  [PKG_CHECK_MODULES([GLADE_LIB], [libglade-2.0], [have_glade_lib=1], AC_MSG_ERROR([glade requested but not found]))],
+  [test "x$with_glade" = "xno"],
+  [have_glade_lib=0]
+)
+AC_SUBST([HAVE_GLADE_LIB], [$have_glade_lib])
+
+AS_IF(
+  [test "x$with_vte" = "xyes"],
+  [PKG_CHECK_MODULES([VTE], [vte >= 0.23.5], [have_vte=1], AC_MSG_ERROR([vte requested but not found]))],
+  [test "x$with_vte" = "xno"],
+  [have_vte=0]
+)
+AC_SUBST([HAVE_VTE], [$have_vte])
 
 # Checks for header files.
 AC_CHECK_HEADERS([locale.h])