diff --git a/doc/undoc-flags.json b/doc/undoc-flags.json
deleted file mode 100644
index 5f1822cea..000000000
--- a/doc/undoc-flags.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-    "flags": [
-        "channel-fee-max-base-msat",
-        "channel-fee-max-proportional-thousandths",
-        "funder-fund-probability",
-        "funder-fuzz-percent",
-        "funder-lease-requests-only",
-        "funder-max-their-funding",
-        "funder-min-their-funding",
-        "funder-per-channel-max",
-        "funder-per-channel-min",
-        "funder-policy",
-        "funder-policy-mod",
-        "funder-reserve-tank",
-        "lease-fee-base-sat",
-        "lease-fee-base-msat",
-        "lease-fee-basis",
-        "lease-funding-weight"
-    ]
-}
diff --git a/doc/undoc-flags.list b/doc/undoc-flags.list
new file mode 100644
index 000000000..8096c25f8
--- /dev/null
+++ b/doc/undoc-flags.list
@@ -0,0 +1,21 @@
+list-features-only
+test-daemons-only
+renepay-debug-mcf
+renepay-debug-payflow
+require-confirmed-inputs=
+channel-fee-max-base-msat=
+channel-fee-max-proportional-thousandths=
+funder-fund-probability=
+funder-fuzz-percent=
+funder-lease-requests-only=
+funder-max-their-funding=
+funder-min-their-funding=
+funder-per-channel-max=
+funder-per-channel-min=
+funder-policy=
+funder-policy-mod=
+funder-reserve-tank=
+lease-fee-base-sat=
+lease-fee-base-msat=
+lease-fee-basis=
+lease-funding-weight=
diff --git a/tools/check-manpage.sh b/tools/check-manpage.sh
index 6a429b847..d333fd1b8 100755
--- a/tools/check-manpage.sh
+++ b/tools/check-manpage.sh
@@ -28,8 +28,18 @@ get_cmd_opts()
     done
 }
 
+# Remove undocumented proprieties, usually these proprieties are
+# under experimental phases.
+remove_undoc()
+{
+    # shellcheck disable=SC2162
+    while read OPT; do
+	grep -q "^$OPT$" < doc/undoc-flags.list || echo "$OPT"
+    done
+}
+
 # If we don't get any, we failed!
-CMD_OPTNAMES=$(get_cmd_opts "$1" | sort)
+CMD_OPTNAMES=$(get_cmd_opts "$1" | sort | remove_undoc)
 if [ -z "$CMD_OPTNAMES" ]; then
     echo "Failed to get options from $0!" >&2
     exit 1
@@ -38,16 +48,6 @@ fi
 # Now, gather (long) opt names from man page, make sure they match.
 MAN_OPTNAMES=$(grep -vi 'deprecated in' "$2" | sed -E -n 's,^\* \*\*(--)?([^*/]*)\*\*(/\*\*-.\*\*)?(=?).*,\2\4,p'| sort)
 
-# Remove undocumented proprieties, usually these proprieties are
-# under experimental phases.
-for flag in $(jq '.flags[]' <doc/undoc-flags.json) ; do
-    # Remove the quotes from the string, so the code will remove
-    # the first and last char in the string.
-    FLAG=$(sed 's/.//;s/.$//' <(echo "$flag"))
-    CMD_OPTNAMES=$(sed "/$FLAG=/d" <(echo "$CMD_OPTNAMES"))
-done
-
-
 if [ "$CMD_OPTNAMES" != "$MAN_OPTNAMES" ]; then
     echo "diff of command names vs manpage names":
     diff -u --label="$1" <(echo "$CMD_OPTNAMES") --label="$2" <(echo "$MAN_OPTNAMES")