diff --git a/.travis.yml b/.travis.yml
index e5c59af..c7f7d14 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,9 +11,9 @@
         - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH
       script:
         - cargo test
-        - cargo build --features unstable
+        - cargo build --features nightly
         - RUSTFLAGS='--cfg procmacro2_unstable' cargo test
-        - RUSTFLAGS='--cfg procmacro2_unstable' cargo build --features unstable
+        - RUSTFLAGS='--cfg procmacro2_unstable' cargo build --features nightly
         - RUSTFLAGS='--cfg procmacro2_unstable' cargo doc --no-deps
       after_success:
         - travis-cargo --only nightly doc-upload
diff --git a/Cargo.toml b/Cargo.toml
index 19e860f..ac33607 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,4 +21,13 @@
 unicode-xid = "0.1"
 
 [features]
-unstable = []
+
+# When enabled: act as a shim around the nightly compiler's proc_macro crate.
+# This requires a nightly compiler.
+#
+# When disabled: emulate the same API as the nightly compiler's proc_macro crate
+# but in a way that works on all stable compilers >=1.15.0.
+nightly = []
+
+# Deprecated; use "nightly" instead.
+unstable = ["nightly"]
diff --git a/README.md b/README.md
index c26ec75..665678b 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,7 @@
 }
 ```
 
-If you'd like you can enable the `unstable` feature in this crate. This will
+If you'd like you can enable the `nightly` feature in this crate. This will
 cause it to compile against the **unstable and nightly-only** features of the
 `proc_macro` crate. This in turn requires a nightly compiler. This should help
 preserve span information, however, coming in from the compiler itself.
@@ -57,7 +57,7 @@
 
 ```toml
 [dependencies]
-proc-macro2 = { version = "0.1", features = ["unstable"] }
+proc-macro2 = { version = "0.1", features = ["nightly"] }
 ```
 
 
diff --git a/src/lib.rs b/src/lib.rs
index 26d3244..153b9c8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -14,16 +14,16 @@
 //! to use this crate will be trivially able to switch to the upstream
 //! `proc_macro` crate once its API stabilizes.
 //!
-//! In the meantime this crate also has an `unstable` Cargo feature which
+//! In the meantime this crate also has a `nightly` Cargo feature which
 //! enables it to reimplement itself with the unstable API of `proc_macro`.
 //! This'll allow immediate usage of the beneficial upstream API, particularly
 //! around preserving span information.
 
-#![cfg_attr(feature = "unstable", feature(proc_macro))]
+#![cfg_attr(feature = "nightly", feature(proc_macro))]
 
 extern crate proc_macro;
 
-#[cfg(not(feature = "unstable"))]
+#[cfg(not(feature = "nightly"))]
 extern crate unicode_xid;
 
 use std::fmt;
@@ -31,14 +31,14 @@
 use std::iter::FromIterator;
 
 #[macro_use]
-#[cfg(not(feature = "unstable"))]
+#[cfg(not(feature = "nightly"))]
 mod strnom;
 
 #[path = "stable.rs"]
-#[cfg(not(feature = "unstable"))]
+#[cfg(not(feature = "nightly"))]
 mod imp;
 #[path = "unstable.rs"]
-#[cfg(feature = "unstable")]
+#[cfg(feature = "nightly")]
 mod imp;
 
 #[macro_use]
@@ -162,8 +162,8 @@
         Span(imp::Span::def_site())
     }
 
-    /// This method is only available when the `"unstable"` feature is enabled.
-    #[cfg(feature = "unstable")]
+    /// This method is only available when the `"nightly"` feature is enabled.
+    #[cfg(feature = "nightly")]
     pub fn unstable(self) -> proc_macro::Span {
         self.0.unstable()
     }
diff --git a/tests/test.rs b/tests/test.rs
index 6442ba6..8320876 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -6,7 +6,7 @@
 use proc_macro2::TokenNode;
 
 #[cfg(procmacro2_unstable)]
-#[cfg(not(feature = "unstable"))]
+#[cfg(not(feature = "nightly"))]
 use proc_macro2::Span;
 
 #[test]
@@ -121,7 +121,7 @@
 }
 
 #[cfg(procmacro2_unstable)]
-#[cfg(not(feature = "unstable"))]
+#[cfg(not(feature = "nightly"))]
 #[test]
 fn default_span() {
     let start = Span::call_site().start();