diff --git a/serde/src/ser/mod.rs b/serde/src/ser/mod.rs
index 971cc50a..e0cc35a5 100644
--- a/serde/src/ser/mod.rs
+++ b/serde/src/ser/mod.rs
@@ -127,9 +127,10 @@ pub trait Serializer {
 
     #[inline]
     fn visit_enum_simple<T>(&mut self,
-                            _name: &str,
-                            _variant: &str,
-                            _value: T) -> Result<(), Self::Error>
+                            name: &'static str,
+                            variant_index: usize,
+                            variant: &'static str,
+                            value: T) -> Result<(), Self::Error>
         where T: Serialize;
 
     fn visit_none(&mut self) -> Result<(), Self::Error>;
diff --git a/serde_codegen/src/ser.rs b/serde_codegen/src/ser.rs
index e20a3a53..7d80f9dd 100644
--- a/serde_codegen/src/ser.rs
+++ b/serde_codegen/src/ser.rs
@@ -309,6 +309,7 @@ fn serialize_variant(
                     ::serde::ser::Serializer::visit_enum_simple(
                         serializer,
                         $type_name,
+                        $variant_index,
                         $variant_name,
                         __simple_value,
                     )
diff --git a/serde_json/src/ser.rs b/serde_json/src/ser.rs
index 5b546e3e..c1368833 100644
--- a/serde_json/src/ser.rs
+++ b/serde_json/src/ser.rs
@@ -174,6 +174,7 @@ impl<W, F> ser::Serializer for Serializer<W, F>
     #[inline]
     fn visit_enum_simple<T>(&mut self,
                             _name: &str,
+                            _variant_index: usize,
                             variant: &str,
                             value: T,
                             ) -> io::Result<()>
diff --git a/serde_json/src/value.rs b/serde_json/src/value.rs
index 794d8b21..ea40cb83 100644
--- a/serde_json/src/value.rs
+++ b/serde_json/src/value.rs
@@ -474,6 +474,7 @@ impl ser::Serializer for Serializer {
     #[inline]
     fn visit_enum_simple<T>(&mut self,
                             _name: &str,
+                            _variant_index: usize,
                             variant: &str,
                             value: T,
                             ) -> Result<(), ()>
diff --git a/serde_tests/tests/test_bytes.rs b/serde_tests/tests/test_bytes.rs
index c7499ffe..b6b31a6d 100644
--- a/serde_tests/tests/test_bytes.rs
+++ b/serde_tests/tests/test_bytes.rs
@@ -41,6 +41,7 @@ impl serde::Serializer for BytesSerializer {
 
     fn visit_enum_simple<T>(&mut self,
                             _name: &str,
+                            _variant_index: usize,
                             _variant: &str,
                             _value: T) -> Result<(), Error>
     {
diff --git a/serde_tests/tests/test_ser.rs b/serde_tests/tests/test_ser.rs
index c667cf35..6b0d8347 100644
--- a/serde_tests/tests/test_ser.rs
+++ b/serde_tests/tests/test_ser.rs
@@ -84,6 +84,7 @@ impl<'a> Serializer for AssertSerializer<'a> {
 
     fn visit_enum_simple<T>(&mut self,
                             name: &str,
+                            _variant_index: usize,
                             variant: &str,
                             value: T,
                             ) -> Result<(), ()>