diff --git a/build.rs b/build.rs
index da1fac5..848878f 100644
--- a/build.rs
+++ b/build.rs
@@ -117,7 +117,7 @@ fn build_src_file(filename: &str) -> PathBuf
 fn compile(src_files: &[PathBuf], output_name: &str) -> PathBuf
 {
    let c_compiler: OsString;
-   let mut output_file: PathBuf;
+   let output_file: PathBuf;
    let mut initial_command: ::std::process::Command;
    let command: &mut ::std::process::Command;
    let last_command: &mut ::std::process::Command;
@@ -188,8 +188,8 @@ fn compile_and_run(output_name: &str, src_files: &[PathBuf], args: &[PathBuf])
 pub fn main()
 {
    let _gen_file: PathBuf;
-   let mut errno_file: PathBuf;
-   let mut gen_errno_file: PathBuf;
+   let errno_file: PathBuf;
+   let gen_errno_file: PathBuf;
 
    errno_file = build_src_file(ERRNO_GENERATOR_FILENAME);
    _gen_file = build_output_file(ERRNO_GENERATOR_OUTPUT_FILENAME);
diff --git a/src/c/errno.rs b/src/c/errno.rs
index 925979c..750cd96 100644
--- a/src/c/errno.rs
+++ b/src/c/errno.rs
@@ -7,7 +7,7 @@ use binding::CInt;
 /// This can be used for clearing an error.
 pub const NO_ERROR: CInt = 0;
 
-/// Include the generated C error values.
+// Include the generated C error values.
 include!(concat!(env!("OUT_DIR"), "/errno_values.rs"));
 
 
@@ -157,11 +157,6 @@ impl Error for CError
             { "Detected an Error not handled by CError" }
       }
    }
-
-   fn get_cause(&self) -> Option<&Error>
-   {
-      None
-   }
 }