diff --git a/src/base.rs b/src/base.rs
index 9cfb0a9..5b8e71c 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -28,7 +28,9 @@ pub type CGFloat = libc::c_float;
 
 pub type CGError = libc::int32_t;
 
-pub type CGAffineTransform = ();
+// This is an enum due to zero-sized types warnings.
+// For more details see https://github.com/rust-lang/rust/issues/27303
+pub enum CGAffineTransform {}
 
 pub const kCGImageAlphaNone: u32 = 0;
 pub const kCGImageAlphaPremultipliedLast: u32 = 1;
diff --git a/src/context.rs b/src/context.rs
index 3347bf5..d6c44d3 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -28,8 +28,9 @@ pub enum CGTextDrawingMode {
     CGTextClip
 }
 
-#[repr(C)]
-pub struct __CGContext;
+// This is an enum due to zero-sized types warnings.
+// For more details see https://github.com/rust-lang/rust/issues/27303
+pub enum __CGContext {}
 
 pub type CGContextRef = *const __CGContext;
 
diff --git a/src/font.rs b/src/font.rs
index 3c1c390..00d3b89 100644
--- a/src/font.rs
+++ b/src/font.rs
@@ -17,8 +17,9 @@ use std::ptr;
 
 pub type CGGlyph = libc::c_ushort;
 
-#[repr(C)]
-pub struct __CGFont;
+// This is an enum due to zero-sized types warnings.
+// For more details see https://github.com/rust-lang/rust/issues/27303
+pub enum __CGFont {}
 
 pub type CGFontRef = *const __CGFont;