diff --git a/src/librustc/ty/query/on_disk_cache.rs b/src/librustc/ty/query/on_disk_cache.rs
index 6e16d92ba0c..19e235154cb 100644
--- a/src/librustc/ty/query/on_disk_cache.rs
+++ b/src/librustc/ty/query/on_disk_cache.rs
@@ -1020,7 +1020,7 @@ impl<'enc, 'a, 'tcx, E> Encoder for CacheEncoder<'enc, 'a, 'tcx, E>
 {
     type Error = E::Error;
 
-    fn emit_nil(&mut self) -> Result<(), Self::Error> {
+    fn emit_unit(&mut self) -> Result<(), Self::Error> {
         Ok(())
     }
 
diff --git a/src/librustc_metadata/encoder.rs b/src/librustc_metadata/encoder.rs
index aae45c17c67..56b38cfbc87 100644
--- a/src/librustc_metadata/encoder.rs
+++ b/src/librustc_metadata/encoder.rs
@@ -75,7 +75,7 @@ macro_rules! encoder_methods {
 impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
     type Error = <opaque::Encoder as Encoder>::Error;
 
-    fn emit_nil(&mut self) -> Result<(), Self::Error> {
+    fn emit_unit(&mut self) -> Result<(), Self::Error> {
         Ok(())
     }
 
diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index 35ef6327de5..9439dc78d3c 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -490,7 +490,7 @@ macro_rules! emit_enquoted_if_mapkey {
 impl<'a> ::Encoder for Encoder<'a> {
     type Error = EncoderError;
 
-    fn emit_nil(&mut self) -> EncodeResult {
+    fn emit_unit(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         write!(self.writer, "null")?;
         Ok(())
@@ -648,7 +648,7 @@ impl<'a> ::Encoder for Encoder<'a> {
     }
     fn emit_option_none(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        self.emit_nil()
+        self.emit_unit()
     }
     fn emit_option_some<F>(&mut self, f: F) -> EncodeResult where
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
@@ -740,7 +740,7 @@ impl<'a> PrettyEncoder<'a> {
 impl<'a> ::Encoder for PrettyEncoder<'a> {
     type Error = EncoderError;
 
-    fn emit_nil(&mut self) -> EncodeResult {
+    fn emit_unit(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         write!(self.writer, "null")?;
         Ok(())
@@ -923,7 +923,7 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     }
     fn emit_option_none(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        self.emit_nil()
+        self.emit_unit()
     }
     fn emit_option_some<F>(&mut self, f: F) -> EncodeResult where
         F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
@@ -1016,7 +1016,7 @@ impl Encodable for Json {
             Json::Boolean(v) => v.encode(e),
             Json::Array(ref v) => v.encode(e),
             Json::Object(ref v) => v.encode(e),
-            Json::Null => e.emit_nil(),
+            Json::Null => e.emit_unit(),
         }
     }
 }
diff --git a/src/libserialize/opaque.rs b/src/libserialize/opaque.rs
index c71f4748911..4ce80bc36a0 100644
--- a/src/libserialize/opaque.rs
+++ b/src/libserialize/opaque.rs
@@ -55,7 +55,7 @@ impl serialize::Encoder for Encoder {
     type Error = !;
 
     #[inline]
-    fn emit_nil(&mut self) -> EncodeResult {
+    fn emit_unit(&mut self) -> EncodeResult {
         Ok(())
     }
 
diff --git a/src/libserialize/serialize.rs b/src/libserialize/serialize.rs
index 416be50bfe9..f0b49c3d9bc 100644
--- a/src/libserialize/serialize.rs
+++ b/src/libserialize/serialize.rs
@@ -25,7 +25,7 @@ pub trait Encoder {
     type Error;
 
     // Primitive types:
-    fn emit_nil(&mut self) -> Result<(), Self::Error>;
+    fn emit_unit(&mut self) -> Result<(), Self::Error>;
     fn emit_usize(&mut self, v: usize) -> Result<(), Self::Error>;
     fn emit_u128(&mut self, v: u128) -> Result<(), Self::Error>;
     fn emit_u64(&mut self, v: u64) -> Result<(), Self::Error>;
@@ -537,7 +537,7 @@ impl Decodable for char {
 
 impl Encodable for () {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_nil()
+        s.emit_unit()
     }
 }