diff --git a/src/libstd/num/uint_macros.rs b/src/libstd/num/uint_macros.rs
index f480a3b420f54..bcfdb7cd43ac1 100644
--- a/src/libstd/num/uint_macros.rs
+++ b/src/libstd/num/uint_macros.rs
@@ -48,68 +48,6 @@ mod tests {
         assert_eq!(FromStrRadix::from_str_radix("Z", 10), None::<$T>);
         assert_eq!(FromStrRadix::from_str_radix("_", 2), None::<$T>);
     }
-
-    #[test]
-    fn test_uint_to_str_overflow() {
-        let mut u8_val: u8 = 255_u8;
-        assert_eq!(u8_val.to_string(), "255");
-
-        u8_val += 1 as u8;
-        assert_eq!(u8_val.to_string(), "0");
-
-        let mut u16_val: u16 = 65_535_u16;
-        assert_eq!(u16_val.to_string(), "65535");
-
-        u16_val += 1 as u16;
-        assert_eq!(u16_val.to_string(), "0");
-
-        let mut u32_val: u32 = 4_294_967_295_u32;
-        assert_eq!(u32_val.to_string(), "4294967295");
-
-        u32_val += 1 as u32;
-        assert_eq!(u32_val.to_string(), "0");
-
-        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
-        assert_eq!(u64_val.to_string(), "18446744073709551615");
-
-        u64_val += 1 as u64;
-        assert_eq!(u64_val.to_string(), "0");
-    }
-
-    #[test]
-    fn test_uint_from_str_overflow() {
-        let mut u8_val: u8 = 255_u8;
-        assert_eq!(from_str::<u8>("255"), Some(u8_val));
-        assert_eq!(from_str::<u8>("256"), None);
-
-        u8_val += 1 as u8;
-        assert_eq!(from_str::<u8>("0"), Some(u8_val));
-        assert_eq!(from_str::<u8>("-1"), None);
-
-        let mut u16_val: u16 = 65_535_u16;
-        assert_eq!(from_str::<u16>("65535"), Some(u16_val));
-        assert_eq!(from_str::<u16>("65536"), None);
-
-        u16_val += 1 as u16;
-        assert_eq!(from_str::<u16>("0"), Some(u16_val));
-        assert_eq!(from_str::<u16>("-1"), None);
-
-        let mut u32_val: u32 = 4_294_967_295_u32;
-        assert_eq!(from_str::<u32>("4294967295"), Some(u32_val));
-        assert_eq!(from_str::<u32>("4294967296"), None);
-
-        u32_val += 1 as u32;
-        assert_eq!(from_str::<u32>("0"), Some(u32_val));
-        assert_eq!(from_str::<u32>("-1"), None);
-
-        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
-        assert_eq!(from_str::<u64>("18446744073709551615"), Some(u64_val));
-        assert_eq!(from_str::<u64>("18446744073709551616"), None);
-
-        u64_val += 1 as u64;
-        assert_eq!(from_str::<u64>("0"), Some(u64_val));
-        assert_eq!(from_str::<u64>("-1"), None);
-    }
 }
 
 ) }
diff --git a/src/libstd/num/usize.rs b/src/libstd/num/usize.rs
index 74dd38e13c582..89376abfddb1b 100644
--- a/src/libstd/num/usize.rs
+++ b/src/libstd/num/usize.rs
@@ -20,3 +20,70 @@
 pub use core::usize::{BITS, BYTES, MIN, MAX};
 
 uint_module! { usize }
+
+#[cfg(test)]
+mod tests {
+    use prelude::v1::*;
+
+    #[test]
+    fn test_uint_to_str_overflow() {
+        let mut u8_val: u8 = 255_u8;
+        assert_eq!(u8_val.to_string(), "255");
+
+        u8_val += 1 as u8;
+        assert_eq!(u8_val.to_string(), "0");
+
+        let mut u16_val: u16 = 65_535_u16;
+        assert_eq!(u16_val.to_string(), "65535");
+
+        u16_val += 1 as u16;
+        assert_eq!(u16_val.to_string(), "0");
+
+        let mut u32_val: u32 = 4_294_967_295_u32;
+        assert_eq!(u32_val.to_string(), "4294967295");
+
+        u32_val += 1 as u32;
+        assert_eq!(u32_val.to_string(), "0");
+
+        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
+        assert_eq!(u64_val.to_string(), "18446744073709551615");
+
+        u64_val += 1 as u64;
+        assert_eq!(u64_val.to_string(), "0");
+    }
+
+    #[test]
+    fn test_uint_from_str_overflow() {
+        let mut u8_val: u8 = 255_u8;
+        assert_eq!(from_str::<u8>("255"), Some(u8_val));
+        assert_eq!(from_str::<u8>("256"), None);
+
+        u8_val += 1 as u8;
+        assert_eq!(from_str::<u8>("0"), Some(u8_val));
+        assert_eq!(from_str::<u8>("-1"), None);
+
+        let mut u16_val: u16 = 65_535_u16;
+        assert_eq!(from_str::<u16>("65535"), Some(u16_val));
+        assert_eq!(from_str::<u16>("65536"), None);
+
+        u16_val += 1 as u16;
+        assert_eq!(from_str::<u16>("0"), Some(u16_val));
+        assert_eq!(from_str::<u16>("-1"), None);
+
+        let mut u32_val: u32 = 4_294_967_295_u32;
+        assert_eq!(from_str::<u32>("4294967295"), Some(u32_val));
+        assert_eq!(from_str::<u32>("4294967296"), None);
+
+        u32_val += 1 as u32;
+        assert_eq!(from_str::<u32>("0"), Some(u32_val));
+        assert_eq!(from_str::<u32>("-1"), None);
+
+        let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
+        assert_eq!(from_str::<u64>("18446744073709551615"), Some(u64_val));
+        assert_eq!(from_str::<u64>("18446744073709551616"), None);
+
+        u64_val += 1 as u64;
+        assert_eq!(from_str::<u64>("0"), Some(u64_val));
+        assert_eq!(from_str::<u64>("-1"), None);
+    }
+}