diff --git a/openssl/src/types.rs b/openssl/src/types.rs
index 7302bca9..40831ee8 100644
--- a/openssl/src/types.rs
+++ b/openssl/src/types.rs
@@ -1,25 +1,38 @@
+//! Items used by other types.
+
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
 
+/// A type implemented by wrappers over OpenSSL types.
+///
+/// This should not be implemented by anything outside of this crate; new methods may be added at
+/// any time.
 pub unsafe trait OpenSslType {
+    /// The raw C type.
     type CType;
 
+    /// Constructs an instance of this type from its raw type.
     unsafe fn from_ptr(ptr: *mut Self::CType) -> Self;
 
+    /// Returns a pointer to its raw type.
     fn as_ptr(&self) -> *mut Self::CType;
 }
 
+/// A reference to an OpenSSL type.
 pub struct Ref<T>(UnsafeCell<()>, PhantomData<T>);
 
 impl<T: OpenSslType> Ref<T> {
+    /// Constructs a shared reference to this type from its raw type.
     pub unsafe fn from_ptr<'a>(ptr: *mut T::CType) -> &'a Ref<T> {
         &*(ptr as *mut _)
     }
 
+    /// Constructs a mutable reference to this type from its raw type.
     pub unsafe fn from_ptr_mut<'a>(ptr: *mut T::CType) -> &'a mut Ref<T> {
         &mut *(ptr as *mut _)
     }
 
+    /// Returns a pointer to its raw type.
     pub fn as_ptr(&self) -> *mut T::CType {
         self as *const _ as *mut _
     }