diff --git a/filter_out_explicit.py b/filter_out_explicit.py
new file mode 100755
index 0000000..32277eb
--- /dev/null
+++ b/filter_out_explicit.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+# pylint: disable=C0103
+
+"""
+From a list of subdomains to block,
+filter out the ones explicitely matching a regex.
+It should be already handled by the ad blocker.
+"""
+
+import logging
+import multiprocessing
+import re
+import sys
+import typing
+
+import regexes
+
+
+def explicitely_match(subdomain: str) -> bool:
+    for regex in regexes.REGEXES:
+        if re.match(regex, subdomain + '.'):
+            return True
+    return False
+
+
+if __name__ == '__main__':
+
+    # Parsing arguments
+    assert len(sys.argv) <= 2
+    filename = None
+
+    if len(sys.argv) == 2 and sys.argv[1] != '-':
+        filename = sys.argv[1]
+        textio = open(filename)
+    else:
+        textio = sys.stdin
+
+    # Cleaning input
+    iterator = iter(textio)
+    iterator = map(str.strip, iterator)
+    iterator = filter(None, iterator)
+
+    for subdomain in iterator:
+        if not explicitely_match(subdomain):
+            print(subdomain)
diff --git a/filter_subdomains.sh b/filter_subdomains.sh
index d576b8c..036c467 100755
--- a/filter_subdomains.sh
+++ b/filter_subdomains.sh
@@ -21,6 +21,7 @@ sort -u temp/all_toblock.list > dist/firstparty-trackers.txt
     echo "# Number of source subdomains: $(wc -l temp/all_subdomains.list | cut -d' ' -f1)"
     echo "# Number of known trackers : $(python -c 'import regexes; print(len(regexes.REGEXES))')"
     echo "# Number of blocked subdomains: $(wc -l dist/firstparty-trackers.txt | cut -d' ' -f1)"
+    echo "# Number of first-party subdomains: $(./filter_out_explicit.py dist/firstparty-trackers.txt | wc)"
     echo
     cat dist/firstparty-trackers.txt | while read host;
     do