diff --git a/.travis.yml b/.travis.yml
index 19ef02b..f741543 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,5 +5,9 @@ rust:
   - beta
   - stable
 
+script:
+  - cargo test
+  - cargo test --features="elcapitan"
+
 notifications:
   webhooks: http://build.servo.org:54856/travis
diff --git a/Cargo.toml b/Cargo.toml
index fef99bb..18d4f61 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,10 +3,14 @@ name = "core-graphics"
 description = "Bindings to Core Graphics for OS X"
 homepage = "https://github.com/servo/core-graphics-rs"
 repository = "https://github.com/servo/core-graphics-rs"
-version = "0.4.3"
+version = "0.5.0"
 authors = ["The Servo Project Developers"]
 license = "MIT / Apache-2.0"
 
+[features]
+default = []
+elcapitan = []
+
 [dependencies]
 libc = "0.2"
 core-foundation = "0.2"
diff --git a/src/event.rs b/src/event.rs
index b193426..f68b8a7 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -204,6 +204,7 @@ impl CGEvent {
         }
     }
 
+    #[cfg(feature = "elcapitan")]
     pub fn post_to_pid(&self, pid: libc::pid_t) {
         unsafe {
             CGEventPostToPid(pid, self.as_concrete_TypeRef());
@@ -268,6 +269,7 @@ extern {
     /// taps.
     fn CGEventPost(tapLocation: CGEventTapLocation, event: CGEventRef);
 
+    #[cfg(feature = "elcapitan")]
     /// Post an event to a specified process ID
     fn CGEventPostToPid(pid: libc::pid_t, event: CGEventRef);