diff --git a/misc/blocklists/append_ipv4.sh b/misc/blocklists/append_ipv4.sh
new file mode 100755
index 0000000..c389451
--- /dev/null
+++ b/misc/blocklists/append_ipv4.sh
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+set -euo pipefail;
+
+LIST_FILE="$(dirname "$0")/ipv4.txt";
+TMP_FILE="$(mktemp)";
+
+IP_REGEX='(?<!\d)\d+(\.\d+){3}(?!\d)';
+
+cat "$LIST_FILE" "$@" |
+    grep --only-matching --perl-regexp "$IP_REGEX" |
+    sort --version-sort |
+    uniq > "$TMP_FILE";
+
+echo "$TMP_FILE";
+if diff "$LIST_FILE" "$TMP_FILE"; then
+    echo "No differences found!";
+    exit 0;
+fi
+
+echo "Press enter to approve changes, ^C to abort";
+read;
+
+mv "$TMP_FILE" "$LIST_FILE";