diff --git a/src/settings/mod.rs b/src/settings/mod.rs
index c29f780..1b6c02e 100644
--- a/src/settings/mod.rs
+++ b/src/settings/mod.rs
@@ -284,32 +284,36 @@ impl Settings {
         RULESET_CURRENT_VERSION.to_string()
     }
 
-    // TODO make the return type a Result
-    fn update_rules(&self) -> Vec<(Regex, String)> {
+    fn update_rules(&self) -> std::result::Result<Vec<(Regex, String)>, String> {
         let mut rules = self.rules.clone();
 
-        // TODO Optimize that shit
         // TODO break categories in different rules
-        for (category, content) in &self.categories {
-            let mut temp_rules: Vec<(Regex, String)> = Vec::new();
-            for (from, to) in &rules {
-                let from = Regex::new(
-                    from.to_string()
-                        .replace(
+        for (from, to) in rules.iter_mut() {
+            let re = Regex::new("%\\D");
+            let from_match = re.is_match(from.as_str());
+            let to_match = re.is_match(to);
+            if from_match || to_match {
+                for (category, content) in &self.categories {
+                    if from_match {
+                        *from = Regex::new(
+                            from.to_string()
+                                .replace(
+                                    format!("%{}", category).as_str(),
+                                    format!("[{}]", content).as_str(),
+                                )
+                                .as_str()
+                        );
+                    }
+                    if to_match {
+                        *to = to.to_string().replace(
                             format!("%{}", category).as_str(),
-                            format!("[{}]", content).as_str(),
-                        )
-                        .as_str(),
-                );
-                let to = to.to_string().replace(
-                    format!("%{}", category).as_str(),
-                    format!("[{}]", content).as_str(),
-                );
-                temp_rules.push((from, to));
+                            format!("[{}]", content).as_str()
+                        );
+                    }
+                }
             }
-            rules = temp_rules.clone();
         }
-        rules
+        Ok(rules)
     }
 
     /// Apply list of rules to input
@@ -337,7 +341,8 @@ impl Settings {
     /// let _output = settings.apply(input);
     /// ```
     pub fn apply(&self, s: String) -> std::result::Result<String, String> {
-        let rules = self.update_rules();
+        // TODO Add Error handling
+        let rules = self.update_rules().unwrap();
         let mut s = s.clone();
         debug!("===============================================");
         for (from, to) in rules {