diff --git a/mkfs/Makefile b/mkfs/Makefile
index 6c7ee18..a0c168e 100644
--- a/mkfs/Makefile
+++ b/mkfs/Makefile
@@ -15,7 +15,8 @@
 	lts_5.4.conf \
 	lts_5.10.conf \
 	lts_5.15.conf \
-	lts_6.1.conf
+	lts_6.1.conf \
+	lts_6.6.conf
 
 LLDLIBS += $(LIBXFS) $(LIBXCMD) $(LIBFROG) $(LIBRT) $(LIBBLKID) \
 	$(LIBUUID) $(LIBINIH) $(LIBURCU) $(LIBPTHREAD)
diff --git a/mkfs/lts_6.6.conf b/mkfs/lts_6.6.conf
new file mode 100644
index 0000000..244f8ea
--- /dev/null
+++ b/mkfs/lts_6.6.conf
@@ -0,0 +1,14 @@
+# V5 features that were the mkfs defaults when the upstream Linux 6.6 LTS
+# kernel was released at the end of 2023.
+
+[metadata]
+bigtime=1
+crc=1
+finobt=1
+inobtcount=1
+reflink=1
+rmapbt=1
+
+[inode]
+sparse=1
+nrext64=1