diff --git a/serde_derive/src/de.rs b/serde_derive/src/de.rs
index df76ec63..4c788845 100644
--- a/serde_derive/src/de.rs
+++ b/serde_derive/src/de.rs
@@ -61,7 +61,12 @@ pub fn expand_derive_deserialize(input: &syn::DeriveInput) -> Result<TokenStream
         }
     };
 
-    Ok(dummy::wrap_in_const(cont.attrs.custom_serde_path(), "DESERIALIZE", ident, impl_block))
+    Ok(dummy::wrap_in_const(
+        cont.attrs.custom_serde_path(),
+        "DESERIALIZE",
+        ident,
+        impl_block,
+    ))
 }
 
 fn precondition(cx: &Ctxt, cont: &Container) {
diff --git a/serde_derive/src/dummy.rs b/serde_derive/src/dummy.rs
index a4e0e038..f77cbbe5 100644
--- a/serde_derive/src/dummy.rs
+++ b/serde_derive/src/dummy.rs
@@ -3,7 +3,12 @@ use proc_macro2::{Ident, Span, TokenStream};
 use syn;
 use try;
 
-pub fn wrap_in_const(serde_path: Option<&syn::Path>, trait_: &str, ty: &Ident, code: TokenStream) -> TokenStream {
+pub fn wrap_in_const(
+    serde_path: Option<&syn::Path>,
+    trait_: &str,
+    ty: &Ident,
+    code: TokenStream,
+) -> TokenStream {
     let try_replacement = try::replacement();
 
     let dummy_const = Ident::new(
@@ -11,16 +16,20 @@ pub fn wrap_in_const(serde_path: Option<&syn::Path>, trait_: &str, ty: &Ident, c
         Span::call_site(),
     );
 
-    let use_serde = serde_path.map(|path| {
-        quote!(use #path as _serde;)
-    }).unwrap_or_else(|| {
-        quote! {
-            #[allow(unknown_lints)]
-            #[cfg_attr(feature = "cargo-clippy", allow(useless_attribute))]
-            #[allow(rust_2018_idioms)]
-            extern crate serde as _serde;
-        }
-    });
+    let use_serde = serde_path
+        .map(|path| {
+            quote! {
+                use #path as _serde;
+            }
+        })
+        .unwrap_or_else(|| {
+            quote! {
+                #[allow(unknown_lints)]
+                #[cfg_attr(feature = "cargo-clippy", allow(useless_attribute))]
+                #[allow(rust_2018_idioms)]
+                extern crate serde as _serde;
+            }
+        });
 
     quote! {
         #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
diff --git a/serde_derive/src/ser.rs b/serde_derive/src/ser.rs
index d5c83bc6..c5388aff 100644
--- a/serde_derive/src/ser.rs
+++ b/serde_derive/src/ser.rs
@@ -52,7 +52,12 @@ pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<TokenStream,
         }
     };
 
-    Ok(dummy::wrap_in_const(cont.attrs.custom_serde_path(), "SERIALIZE", ident, impl_block))
+    Ok(dummy::wrap_in_const(
+        cont.attrs.custom_serde_path(),
+        "SERIALIZE",
+        ident,
+        impl_block,
+    ))
 }
 
 fn precondition(cx: &Ctxt, cont: &Container) {
diff --git a/test_suite/tests/test_gen.rs b/test_suite/tests/test_gen.rs
index 92bb0ae1..bd60488c 100644
--- a/test_suite/tests/test_gen.rs
+++ b/test_suite/tests/test_gen.rs
@@ -265,7 +265,7 @@ fn test_gen() {
     #[cfg(feature = "unstable")]
     #[derive(Serialize, Deserialize)]
     struct NonAsciiIdents {
-        σ: f64,
+        σ:  f64,
     }
 
     #[derive(Serialize, Deserialize)]
diff --git a/test_suite/tests/test_serde_path.rs b/test_suite/tests/test_serde_path.rs
index 4de43673..68971619 100644
--- a/test_suite/tests/test_serde_path.rs
+++ b/test_suite/tests/test_serde_path.rs
@@ -19,7 +19,8 @@ mod fake_serde {
     where
         T: Serialize,
         T: for<'a> Deserialize<'a>,
-    {}
+    {
+    }
 
     pub trait Serialize {
         fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error>;