diff --git a/src/lib.rs b/src/lib.rs
index 75b3701..b491191 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,14 +66,14 @@ pub extern fn read_data(png_ptr: *mut ffi::png_struct, data: *mut u8, length: si
     }
 }
 
-pub fn load_png<P: AsPath + ?Sized>(path: &P) -> Result<Image, String> {
+pub fn load_png<P: AsPath>(path: P) -> Result<Image, String> {
     let mut reader = match File::open(path) {
         Ok(r) => r,
         Err(e) => return Err(format!("could not open file: {}", e.description())),
     };
     let mut buffer = vec![];
     match reader.read_to_end(&mut buffer) {
-        Ok(()) => (),
+        Ok(_) => (),
         Err(e) => return Err(format!("could not read file: {}", e.description())),
     }
     load_png_from_memory(&buffer)
@@ -191,7 +191,7 @@ pub extern fn flush_data(png_ptr: *mut ffi::png_struct) {
     }
 }
 
-pub fn store_png<P: AsPath + ?Sized>(img: &mut Image, path: &P) -> Result<(),String> {
+pub fn store_png<P: AsPath>(img: &mut Image, path: P) -> Result<(),String> {
     let mut file = match File::create(path) {
         Ok(f) => f,
         Err(e) => return Err(format!("{}", e))
@@ -307,7 +307,7 @@ mod test {
         };
         let mut buf = vec![];
         match reader.read_to_end(&mut buf) {
-            Ok(()) => (),
+            Ok(_) => (),
             Err(e) => panic!(e)
         }
         b.bench_n(1, |b| b.iter(|| {