diff --git a/src/base64/base64.rs b/src/base64/base64.rs
index 85e2dd47e..3ea79a7c3 100644
--- a/src/base64/base64.rs
+++ b/src/base64/base64.rs
@@ -68,8 +68,8 @@ pub fn uumain(args: Vec<String>) -> i32 {
         },
         None => 76
     };
-    let mut stdin_buf;
-    let mut file_buf;
+    let stdin_buf;
+    let file_buf;
     let mut input = if matches.free.is_empty() || &matches.free[0][..] == "-" {
         stdin_buf = stdin();
         BufReader::new(Box::new(stdin_buf) as Box<Read+'static>)
diff --git a/src/expand/expand.rs b/src/expand/expand.rs
index cce64f79d..09bf427b1 100644
--- a/src/expand/expand.rs
+++ b/src/expand/expand.rs
@@ -127,7 +127,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
 }
 
 fn open(path: String) -> BufReader<Box<Read+'static>> {
-    let mut file_buf;
+    let file_buf;
     if path == "-" {
         BufReader::new(Box::new(stdin()) as Box<Read>)
     } else {
diff --git a/src/hashsum/hashsum.rs b/src/hashsum/hashsum.rs
index 01908ec18..a47aa1ca1 100644
--- a/src/hashsum/hashsum.rs
+++ b/src/hashsum/hashsum.rs
@@ -169,8 +169,8 @@ fn hashsum<'a>(algoname: &str, mut digest: Box<Digest+'a>, files: Vec<String>, b
     };
     for filename in files.iter() {
         let filename: &str = filename;
-        let mut stdin_buf;
-        let mut file_buf;
+        let stdin_buf;
+        let file_buf;
         let mut file = BufReader::new(
             if filename == "-" {
                 stdin_buf = stdin();
diff --git a/src/unexpand/unexpand.rs b/src/unexpand/unexpand.rs
index 633cd312b..af138dcef 100644
--- a/src/unexpand/unexpand.rs
+++ b/src/unexpand/unexpand.rs
@@ -119,7 +119,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
 }
 
 fn open(path: String) -> BufReader<Box<Read+'static>> {
-    let mut file_buf;
+    let file_buf;
     if path == "-" {
         BufReader::new(Box::new(stdin()) as Box<Read>)
     } else {
diff --git a/test/factor.rs b/test/factor.rs
index a8e8103d8..878ed95de 100644
--- a/test/factor.rs
+++ b/test/factor.rs
@@ -35,7 +35,7 @@ fn test_random() {
         let mut factors = Vec::new();
         while product < min {
             // log distribution---higher probability for lower numbers
-            let mut factor;
+            let factor;
             loop {
                 let next = rng.gen_range(0f64, LOG_PRIMES).exp2().floor() as usize;
                 if next < NUM_PRIMES {