diff --git a/src/opnsense/scripts/dhcp/dnsmasq_watcher.py b/src/opnsense/scripts/dhcp/dnsmasq_watcher.py
index 62c181bcd..be99d8088 100755
--- a/src/opnsense/scripts/dhcp/dnsmasq_watcher.py
+++ b/src/opnsense/scripts/dhcp/dnsmasq_watcher.py
@@ -49,7 +49,7 @@ def run_watcher(target_filename, default_domain, watch_file, service_pid):
     # initiate lease watcher and setup cache
     dhcpdleases = watchers.dhcpd.DHCPDLease(watch_file)
     cached_leases = dict()
-    hostname_pattern = re.compile("(?!-)[A-Z0-9-]*(?<!-)$", re.IGNORECASE)
+    hostname_pattern = re.compile("(?!-)[A-Z0-9-_]*(?<!-)$", re.IGNORECASE)
 
     # start watching dhcp leases
     last_cleanup = time.time()
diff --git a/src/opnsense/scripts/dhcp/unbound_watcher.py b/src/opnsense/scripts/dhcp/unbound_watcher.py
index e56b59f95..429478bc8 100755
--- a/src/opnsense/scripts/dhcp/unbound_watcher.py
+++ b/src/opnsense/scripts/dhcp/unbound_watcher.py
@@ -136,7 +136,7 @@ def run_watcher(target_filename, default_domain, watch_file, config):
     dhcpdleases = watchers.dhcpd.DHCPDLease(watch_file)
     cached_leases = dict()
     unbound_local_data = UnboundLocalData()
-    hostname_pattern = re.compile("(?!-)[A-Z0-9-]*(?<!-)$", re.IGNORECASE)
+    hostname_pattern = re.compile("(?!-)[A-Z0-9-_]*(?<!-)$", re.IGNORECASE)
 
     # start watching dhcp leases
     last_cleanup = time.time()