diff --git a/objc_sys/src/class.rs b/objc_sys/src/class.rs
index 6ea16a8c5..6bcb8e9c7 100644
--- a/objc_sys/src/class.rs
+++ b/objc_sys/src/class.rs
@@ -102,7 +102,7 @@ extern "C" {
         name: *const objc_selector,
         imp: IMP,
         types: *const c_char,
-    ) -> IMP;
+    ) -> Option<IMP>;
     pub fn class_replaceProperty(
         cls: *mut objc_class,
         name: *const c_char,
diff --git a/objc_sys/src/various.rs b/objc_sys/src/various.rs
index df0e92c5c..af068bdc7 100644
--- a/objc_sys/src/various.rs
+++ b/objc_sys/src/various.rs
@@ -12,8 +12,7 @@ pub struct objc_ivar {
 
 /// A pointer to the start of a method implementation.
 ///
-/// Remember that this is non-null!
-/// Use `Option<IMP>` where nullability is expected. TODO
+/// This must be non-null. Use `Option<IMP>` when nullability is desired.
 pub type IMP = unsafe extern "C" fn();
 
 /// Not available on macOS x86.