diff --git a/gstreamer-video/src/video_frame.rs b/gstreamer-video/src/video_frame.rs
index 5adfa28bd..5b902ed6e 100644
--- a/gstreamer-video/src/video_frame.rs
+++ b/gstreamer-video/src/video_frame.rs
@@ -20,8 +20,9 @@ use std::ops;
 use std::ptr;
 use std::slice;
 
-pub struct Readable;
-pub struct Writable;
+pub enum Readable {}
+pub enum Writable {}
+
 pub struct VideoFrame<T>(
     ffi::GstVideoFrame,
     Option<gst::Buffer>,
diff --git a/gstreamer/src/buffer.rs b/gstreamer/src/buffer.rs
index b67442bd9..59a56f802 100644
--- a/gstreamer/src/buffer.rs
+++ b/gstreamer/src/buffer.rs
@@ -24,8 +24,8 @@ use glib;
 use glib::translate::{from_glib, from_glib_full, ToGlib};
 use glib_ffi;
 
-pub struct Readable;
-pub struct Writable;
+pub enum Readable {}
+pub enum Writable {}
 
 #[repr(C)]
 pub struct BufferRef(ffi::GstBuffer);
diff --git a/gstreamer/src/tags.rs b/gstreamer/src/tags.rs
index 29072d690..b50852e8a 100644
--- a/gstreamer/src/tags.rs
+++ b/gstreamer/src/tags.rs
@@ -30,7 +30,7 @@ pub trait Tag<'a> {
 
 macro_rules! impl_tag(
     ($name:ident, $t:ty, $rust_tag:ident, $gst_tag:ident) => {
-        pub struct $name;
+        pub enum $name {}
         impl<'a> Tag<'a> for $name {
             type TagType = $t;
             fn tag_name<'b>() -> &'b str {