diff --git a/src/common/c_types.rs b/src/common/c_types.rs
index 2330ab17d..b78356f2b 100644
--- a/src/common/c_types.rs
+++ b/src/common/c_types.rs
@@ -186,7 +186,7 @@ unsafe fn get_group_list_internal(name: *const c_char, gid: gid_t, groups: *mut
     }
 }
 
-pub fn get_groups() -> Result<Vec<gid_t>, int> {
+pub fn get_groups() -> Result<Vec<gid_t>, uint> {
     let ngroups = unsafe { getgroups(0, null_mut()) };
     if ngroups == -1 {
         return Err(os::errno());
@@ -210,7 +210,7 @@ pub fn group(possible_pw: Option<c_passwd>, nflag: bool) {
 
     match groups {
         Err(errno) =>
-            crash!(1, "failed to get group list (errno={:d})", errno),
+            crash!(1, "failed to get group list (errno={:u})", errno),
         Ok(groups) => {
             for &g in groups.iter() {
                 if nflag {
diff --git a/src/id/id.rs b/src/id/id.rs
index ce7d1024a..15ef512dc 100644
--- a/src/id/id.rs
+++ b/src/id/id.rs
@@ -345,7 +345,7 @@ fn id_print(possible_pw: Option<c_passwd>,
     };
 
     let groups = groups.unwrap_or_else(|errno| {
-        crash!(1, "failed to get group list (errno={:d})", errno);
+        crash!(1, "failed to get group list (errno={:u})", errno);
     });
 
     if possible_pw.is_some() {
diff --git a/src/mkfifo/mkfifo.rs b/src/mkfifo/mkfifo.rs
index b53b64df5..9b4f7b549 100644
--- a/src/mkfifo/mkfifo.rs
+++ b/src/mkfifo/mkfifo.rs
@@ -69,7 +69,7 @@ pub fn uumain(args: Vec<String>) -> int {
         f.with_c_str(|name| {
             let err = unsafe { mkfifo(name, mode) };
             if err == -1 {
-                show_error!("creating '{}': {}", f, os::error_string(os::errno() as uint));
+                show_error!("creating '{}': {}", f, os::error_string(os::errno()));
                 exit_status = 1;
             }
         });