diff --git a/src/nvim.rs b/src/nvim.rs
index 99a4feb..3e4964f 100644
--- a/src/nvim.rs
+++ b/src/nvim.rs
@@ -18,7 +18,7 @@ pub trait RedrawEvents {
 
     fn on_redraw(&self);
 
-    fn on_highlight_set(&mut self, attrs: &HashMap<String, Value>);
+    fn on_highlight_set(&mut self, attrs: &HashMap<&str, &Value>);
 
     fn on_eol_clear(&mut self);
 
@@ -150,9 +150,9 @@ fn call(ui: &mut Ui, method: &str, args: &Vec<Value>) -> result::Result<(), Stri
         "resize" => ui.on_resize(try_uint!(args[0]), try_uint!(args[1])),
         "highlight_set" => {
             if let Value::Map(ref attrs) = args[0] {
-                let attrs_map: HashMap<String, Value> = attrs.iter()
+                let attrs_map = attrs.iter()
                     .map(|v| match v {
-                        &(Value::String(ref key), ref value) => (key.clone(), value.clone()),
+                        &(Value::String(ref key), ref value) => (key.as_str(), value),
                         _ => panic!("attribute key must be string"),
                     })
                     .collect();
diff --git a/src/ui.rs b/src/ui.rs
index 8a0fb4d..aa61851 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -451,7 +451,7 @@ impl RedrawEvents for Ui {
     }
 
     fn on_put(&mut self, text: &str) {
-        self.model.put(text, &self.cur_attrs);
+        self.model.put(text, self.cur_attrs.as_ref());
     }
 
     fn on_clear(&mut self) {
@@ -478,15 +478,15 @@ impl RedrawEvents for Ui {
         self.model.scroll(count);
     }
 
-    fn on_highlight_set(&mut self, attrs: &HashMap<String, Value>) {
+    fn on_highlight_set(&mut self, attrs: &HashMap<&str, &Value>) {
         let mut model_attrs = Attrs::new();
-        if let Some(&Value::Integer(Integer::U64(fg))) = attrs.get("foreground") {
+        if let Some(&&Value::Integer(Integer::U64(fg))) = attrs.get("foreground") {
             model_attrs.foreground = Some(split_color(fg));
         }
-        if let Some(&Value::Integer(Integer::U64(bg))) = attrs.get("background") {
+        if let Some(&&Value::Integer(Integer::U64(bg))) = attrs.get("background") {
             model_attrs.background = Some(split_color(bg));
         }
-        if let Some(&Value::Integer(Integer::U64(bg))) = attrs.get("special") {
+        if let Some(&&Value::Integer(Integer::U64(bg))) = attrs.get("special") {
             model_attrs.special = Some(split_color(bg));
         }
         if attrs.contains_key("reverse") {
diff --git a/src/ui_model.rs b/src/ui_model.rs
index 15bbd50..e8939cb 100644
--- a/src/ui_model.rs
+++ b/src/ui_model.rs
@@ -113,10 +113,10 @@ impl UiModel {
         (self.cur_row, self.cur_col)
     }
 
-    pub fn put(&mut self, text: &str, attrs: &Option<Attrs>) {
+    pub fn put(&mut self, text: &str, attrs: Option<&Attrs>) {
         let mut cell = &mut self.model[self.cur_row][self.cur_col];
         cell.ch = text.chars().last().unwrap();
-        cell.attrs = attrs.as_ref().map(|o| o.clone()).unwrap_or_else(|| Attrs::new());
+        cell.attrs = attrs.map(Attrs::clone).unwrap_or_else(|| Attrs::new());
         self.cur_col += 1;
     }