diff --git a/extensions/Makefile b/extensions/Makefile
index 93ead51..5af234e 100644
--- a/extensions/Makefile
+++ b/extensions/Makefile
@@ -85,6 +85,7 @@
 PF6_EXT_SLIB+=$(PF6_EXT_SLIB_OPTS)
 PFX_EXT_SLIB+=$(PFX_EXT_SLIB_OPTS)
 
+OPTIONALS+=$(patsubst %,XT:%,$(PFX_EXT_SLIB_OPTS))
 OPTIONALS+=$(patsubst %,IPv4:%,$(PF_EXT_SLIB_OPTS))
 OPTIONALS+=$(patsubst %,IPv6:%,$(PF6_EXT_SLIB_OPTS))