diff --git a/.travis.yml b/.travis.yml
index 725034c..35ad0b3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,8 +24,8 @@ matrix:
         - cargo fmt -- --write-mode=diff
 
     # Clippy
-    - env: CLIPPY_VERSION="0.0.191"
-      rust: nightly-2018-04-01
+    - env: CLIPPY_VERSION="0.0.212"
+      rust: nightly-2018-10-05
       install:
       - travis_wait cargo install clippy --version $CLIPPY_VERSION || echo "clippy already installed"
       script:
diff --git a/yaserde_derive/src/de/expand_enum.rs b/yaserde_derive/src/de/expand_enum.rs
index f967a8b..b523564 100644
--- a/yaserde_derive/src/de/expand_enum.rs
+++ b/yaserde_derive/src/de/expand_enum.rs
@@ -151,7 +151,7 @@ pub fn parse(
     .map(|variant| {
       let field_attrs = YaSerdeAttribute::parse(&variant.attrs);
       let renamed_label = match field_attrs.rename {
-        Some(value) => Ident::new(&format!("{}", value), Span::call_site()),
+        Some(value) => Ident::new(&value.to_string(), Span::call_site()),
         None => variant.ident.clone(),
       };
       let label = &variant.ident;
diff --git a/yaserde_derive/src/de/expand_struct.rs b/yaserde_derive/src/de/expand_struct.rs
index bdb8461..a2574ee 100644
--- a/yaserde_derive/src/de/expand_struct.rs
+++ b/yaserde_derive/src/de/expand_struct.rs
@@ -130,7 +130,7 @@ pub fn parse(
     .map(|field| {
       let field_attrs = YaSerdeAttribute::parse(&field.attrs);
       let label_name = if let Some(value) = field_attrs.rename {
-        Ident::new(&format!("{}", value), Span::call_site()).to_string()
+        Ident::new(&value.to_string(), Span::call_site()).to_string()
       } else {
         field.ident.clone().unwrap().to_string()
       };
@@ -313,7 +313,7 @@ pub fn parse(
       }
 
       let label_name = if let Some(value) = field_attrs.rename {
-        Ident::new(&format!("{}", value), Span::call_site()).to_string()
+        Ident::new(&value.to_string(), Span::call_site()).to_string()
       } else {
         field.ident.clone().unwrap().to_string()
       };
@@ -781,7 +781,7 @@ pub fn parse(
 
       let label = &field.ident;
       let label_name = if let Some(value) = field_attrs.rename {
-        Ident::new(&format!("{}", value), Span::call_site()).to_string()
+        Ident::new(&value.to_string(), Span::call_site()).to_string()
       } else {
         field.ident.clone().unwrap().to_string()
       };
diff --git a/yaserde_derive/src/ser/expand_enum.rs b/yaserde_derive/src/ser/expand_enum.rs
index 08ca73e..67542f1 100644
--- a/yaserde_derive/src/ser/expand_enum.rs
+++ b/yaserde_derive/src/ser/expand_enum.rs
@@ -19,7 +19,7 @@ pub fn serialize(
     .map(|variant| {
       let variant_attrs = YaSerdeAttribute::parse(&variant.attrs);
       let renamed_label = match variant_attrs.rename {
-        Some(value) => Ident::new(&format!("{}", value), Span::call_site()),
+        Some(value) => Ident::new(&value.to_string(), Span::call_site()),
         None => variant.ident.clone(),
       };
       let label = &variant.ident;
@@ -55,7 +55,7 @@ pub fn serialize(
               }
 
               let renamed_field_label = match field_attrs.rename {
-                Some(value) => Some(Ident::new(&format!("{}", value), Span::call_site())),
+                Some(value) => Some(Ident::new(&value.to_string(), Span::call_site())),
                 None => field.ident.clone(),
               };
               let field_label_name = renamed_field_label.unwrap().to_string();
diff --git a/yaserde_derive/src/ser/expand_struct.rs b/yaserde_derive/src/ser/expand_struct.rs
index 76fd7d0..f65dddd 100644
--- a/yaserde_derive/src/ser/expand_struct.rs
+++ b/yaserde_derive/src/ser/expand_struct.rs
@@ -23,7 +23,7 @@ pub fn serialize(
       }
 
       let renamed_label = match field_attrs.rename {
-        Some(value) => Ident::new(&format!("{}", value), Span::call_site()),
+        Some(value) => Ident::new(&value.to_string(), Span::call_site()),
         None => field.ident.clone().unwrap(),
       };
       let label = &field.ident;
@@ -165,7 +165,7 @@ pub fn serialize(
       }
 
       let renamed_label = match field_attrs.rename {
-        Some(value) => Ident::new(&format!("{}", value), Span::call_site()),
+        Some(value) => Ident::new(&value.to_string(), Span::call_site()),
         None => field.ident.clone().unwrap(),
       };