-pppgetpass_gtk_CFLAGS = -Wno-deprecated-declarations -Wno-discarded-qualifiers
-pppgetpass_gtk_CFLAGS += @GLIB_CFLAGS@ @GTK_CFLAGS@
-pppgetpass_gtk_LDADD = @GLIB_LIBS@ @GTK_LIBS@
+pppgetpass_gtk_CPPFLAGS = -Wno-deprecated-declarations -Wno-discarded-qualifiers
+pppgetpass_gtk_CPPFLAGS += $(GLIB_CFLAGS) $(GTK_CFLAGS)
+pppgetpass_gtk_LDADD = $(GLIB_LIBS) $(GTK_LIBS)