diff --git a/src/color_space.rs b/src/color_space.rs
index 4117084..9ff558c 100644
--- a/src/color_space.rs
+++ b/src/color_space.rs
@@ -11,6 +11,7 @@ use core_foundation::base::{CFRelease, CFRetain, CFTypeID};
 use foreign_types::ForeignType;
 
 foreign_type! {
+    #[doc(hidden)]
     type CType = ::sys::CGColorSpace;
     fn drop = |p| CFRelease(p as *mut _);
     fn clone = |p| CFRetain(p as *const _) as *mut _;
diff --git a/src/event.rs b/src/event.rs
index ce404c5..e064258 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -92,6 +92,7 @@ pub enum CGEventTapLocation {
 }
 
 foreign_type! {
+    #[doc(hidden)]
     type CType = ::sys::CGEvent;
     fn drop = |p| CFRelease(p as *mut _);
     fn clone = |p| CFRetain(p as *const _) as *mut _;
diff --git a/src/font.rs b/src/font.rs
index 798dd46..9615d51 100644
--- a/src/font.rs
+++ b/src/font.rs
@@ -18,6 +18,7 @@ use libc;
 pub type CGGlyph = libc::c_ushort;
 
 foreign_type! {
+    #[doc(hidden)]
     type CType = ::sys::CGFont;
     fn drop = |p| CFRelease(p as *mut _);
     fn clone = |p| CFRetain(p as *const _) as *mut _;
diff --git a/src/image.rs b/src/image.rs
index c6b57a8..e5f238b 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -27,6 +27,7 @@ pub enum CGImageByteOrderInfo {
 }
 
 foreign_type! {
+    #[doc(hidden)]
     type CType = ::sys::CGImage;
     fn drop = CGImageRelease;
     fn clone = |p| CFRetain(p as *const _) as *mut _;