diff --git a/Cargo.toml b/Cargo.toml
index def0a1563..c8f909b61 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "objc"
-version = "0.2.2"
+version = "0.2.3"
 authors = ["Steven Sheldon"]
 
 description = "Objective-C Runtime bindings and wrapper for Rust."
diff --git a/src/macros.rs b/src/macros.rs
index 7c1b0ccf9..81fa413b8 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1,3 +1,30 @@
+#[doc(hidden)]
+#[macro_export]
+macro_rules! sel_impl {
+    // Declare a function to hide unsafety, otherwise we can trigger the
+    // unused_unsafe lint; see rust-lang/rust#8472
+    ($name:expr) => ({
+        #[inline(always)]
+        fn register_sel(name: &str) -> $crate::runtime::Sel {
+            unsafe {
+                static SEL: ::std::sync::atomic::AtomicPtr<::std::os::raw::c_void> =
+                    ::std::sync::atomic::AtomicPtr::new(0 as *mut _);
+                let ptr = SEL.load(::std::sync::atomic::Ordering::Relaxed);
+                // It should be fine to use `Relaxed` ordering here because `sel_registerName` is
+                // thread-safe.
+                if ptr.is_null() {
+                    let sel = $crate::runtime::sel_registerName(name.as_ptr() as *const _);
+                    SEL.store(sel.as_ptr() as *mut _, ::std::sync::atomic::Ordering::Relaxed);
+                    sel
+                } else {
+                    $crate::runtime::Sel::from_ptr(ptr)
+                }
+            }
+        }
+        register_sel($name)
+    })
+}
+
 /**
 Registers a selector, returning a `Sel`.
 
@@ -12,24 +39,8 @@ let sel = sel!(setObject:forKey:);
 */
 #[macro_export]
 macro_rules! sel {
-    // Declare a function to hide unsafety, otherwise we can trigger the
-    // unused_unsafe lint; see rust-lang/rust#8472
-    ($name:ident) => ({
-        #[inline(always)]
-        fn register_sel(name_with_nul: &str) -> $crate::runtime::Sel {
-            let ptr = name_with_nul.as_ptr() as *const _;
-            unsafe { $crate::runtime::sel_registerName(ptr) }
-        }
-        register_sel(concat!(stringify!($name), '\0'))
-    });
-    ($($name:ident :)+) => ({
-        #[inline(always)]
-        fn register_sel(name_with_nul: &str) -> $crate::runtime::Sel {
-            let ptr = name_with_nul.as_ptr() as *const _;
-            unsafe { $crate::runtime::sel_registerName(ptr) }
-        }
-        register_sel(concat!($(stringify!($name), ':'),+, '\0'))
-    });
+    ($name:ident) => ({sel_impl!(concat!(stringify!($name), '\0'))});
+    ($($name:ident :)+) => ({sel_impl!(concat!($(stringify!($name), ':'),+, '\0'))});
 }
 
 /**
diff --git a/src/runtime.rs b/src/runtime.rs
index 2451307f4..1dae57c9d 100644
--- a/src/runtime.rs
+++ b/src/runtime.rs
@@ -147,6 +147,22 @@ impl Sel {
         };
         str::from_utf8(name.to_bytes()).unwrap()
     }
+
+    /// Wraps a raw pointer to a selector into a `Sel` object.
+    ///
+    /// This is almost never what you want; use `Sel::register()` instead.
+    #[inline]
+    pub unsafe fn from_ptr(ptr: *const c_void) -> Sel {
+        Sel {
+            ptr,
+        }
+    }
+
+    /// Returns a pointer to the raw selector.
+    #[inline]
+    pub fn as_ptr(&self) -> *const c_void {
+        self.ptr
+    }
 }
 
 impl PartialEq for Sel {