diff --git a/src/base64/base64.rs b/src/base64/base64.rs
index d2881e0d3..b8eed44d4 100644
--- a/src/base64/base64.rs
+++ b/src/base64/base64.rs
@@ -95,28 +95,27 @@ pub fn uumain(args: Vec<String>) -> int {
 }
 
 fn decode(input: &mut Reader, ignore_garbage: bool) {
-    let to_decode = match input.read_to_string() {
+    let mut to_decode = match input.read_to_string() {
         Ok(m) => m,
         Err(f) => panic!(f)
     };
 
-    let slice =
-        if ignore_garbage {
-            to_decode.as_slice()
-                .trim_chars(|&: c: char| {
-                    if !c.is_ascii() {
-                        return false;
-                    };
-                    !(c >= 'a' && c <= 'z' ||
-                      c >= 'A' && c <= 'Z' ||
-                      c >= '0' && c <= '9' ||
-                      c == '+' || c == '/' )
-                })
-        } else {
-            to_decode.as_slice()
-        };
+    if ignore_garbage {
+        let mut clean = String::new();
+        clean.extend(to_decode.chars().filter(|&c| {
+            if !c.is_ascii() {
+                false
+            } else {
+                c >= 'a' && c <= 'z' ||
+                c >= 'A' && c <= 'Z' ||
+                c >= '0' && c <= '9' ||
+                c == '+' || c == '/'
+            }
+        }));
+        to_decode = clean;
+    }
 
-    match slice.from_base64() {
+    match to_decode.as_slice().from_base64() {
         Ok(bytes) => {
             let mut out = stdout();
 
diff --git a/src/du/du.rs b/src/du/du.rs
index b545d174c..c56ccde0c 100644
--- a/src/du/du.rs
+++ b/src/du/du.rs
@@ -20,7 +20,6 @@ use std::num::Float;
 use std::option::Option;
 use std::path::Path;
 use std::sync::{Arc, Future};
-use std::str::from_utf8;
 use time::Timespec;
 
 #[path = "../common/util.rs"]
@@ -232,22 +231,22 @@ ers of 1000).",
         Some(s) => {
             let mut found_number = false;
             let mut found_letter = false;
-            let mut numbers = vec!();
-            let mut letters = vec!();
+            let mut numbers = String::new(); 
+            let mut letters = String::new(); 
             for c in s.as_slice().chars() {
                 if found_letter && c.is_digit(10) || !found_number && !c.is_digit(10) {
                     show_error!("invalid --block-size argument '{}'", s);
                     return 1;
                 } else if c.is_digit(10) {
                     found_number = true;
-                    numbers.push(c as u8);
+                    numbers.push(c);
                 } else if c.is_alphabetic() {
                     found_letter = true;
                     letters.push(c);
                 }
             }
-            let number = from_utf8(numbers.as_slice()).ok().unwrap().parse::<uint>().unwrap();
-            let multiple = match String::from_chars(letters.as_slice()).as_slice() {
+            let number = numbers.parse::<uint>().unwrap();
+            let multiple = match letters.as_slice() {
                 "K" => 1024, "M" => 1024 * 1024, "G" => 1024 * 1024 * 1024,
                 "T" => 1024 * 1024 * 1024 * 1024, "P" => 1024 * 1024 * 1024 * 1024 * 1024,
                 "E" => 1024 * 1024 * 1024 * 1024 * 1024 * 1024,
@@ -268,7 +267,7 @@ ers of 1000).",
         None => 1024
     };
 
-    let convert_size = |size: u64| -> String {
+    let convert_size = |&: size: u64| -> String {
         if matches.opt_present("human-readable") || matches.opt_present("si") {
             if size >= MB {
                 format!("{:.1}M", (size as f64) / (MB as f64))
diff --git a/src/realpath/realpath.rs b/src/realpath/realpath.rs
index 05e901a03..a42d03507 100644
--- a/src/realpath/realpath.rs
+++ b/src/realpath/realpath.rs
@@ -51,11 +51,11 @@ pub fn uumain(args: Vec<String>) -> int {
     let zero = opts.opt_present("z");
     let quiet = opts.opt_present("q");
     let mut retcode = 0;
-    opts.free.iter().map(|x|
-        if !resolve_path(x.as_slice(), strip, zero, quiet) {
+    for path in opts.free.iter() {
+        if !resolve_path(path.as_slice(), strip, zero, quiet) {
             retcode = 1
-        }
-    ).last();
+        };
+    }
     retcode
 }