diff --git a/src/environment.rs b/src/environment.rs
index 7cf3569..904e36e 100644
--- a/src/environment.rs
+++ b/src/environment.rs
@@ -1,8 +1,8 @@
 use std::net::Ipv4Addr;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
-use std::str::FromStr;
 
+use minijinja::value::ViaDeserialize;
 use minijinja::{AutoEscape, Environment, path_loader};
 use walkdir::WalkDir;
 
@@ -16,6 +16,13 @@ pub struct PathEnvironment<'a> {
     path: PathBuf,
 }
 
+fn apply_netmask(
+    ip: ViaDeserialize<Ipv4Addr>,
+    netmask: ViaDeserialize<Ipv4Addr>,
+) -> Result<String, minijinja::Error> {
+    Ok((*ip & *netmask).to_string())
+}
+
 impl<'a> PathEnvironment<'a> {
     pub fn new(path: &Path) -> Self {
         let mut env = Environment::new();
@@ -27,10 +34,7 @@ impl<'a> PathEnvironment<'a> {
         env.set_auto_escape_callback(|_| AutoEscape::None);
 
         // Add filters
-        env.add_filter("to_prefix", |netmask: String| {
-            let netmask = Ipv4Addr::from_str(&netmask).map_err(|err| {
-                minijinja::Error::new(minijinja::ErrorKind::InvalidOperation, err.to_string())
-            })?;
+        env.add_filter("to_prefix", |netmask: ViaDeserialize<Ipv4Addr>| {
             let mask = netmask.to_bits();
             let prefix = mask.leading_ones();
 
@@ -44,6 +48,8 @@ impl<'a> PathEnvironment<'a> {
             }
         });
 
+        env.add_function("apply_netmask", apply_netmask);
+
         // Helper function for getting the path to kubeconfig files
         env.add_filter("kubeconfig", move |names: Vec<String>| {
             names