diff --git a/src/libcore/benches/num/dec2flt/mod.rs b/src/libcore/benches/num/dec2flt/mod.rs
index 561a4bee87a..305baa68729 100644
--- a/src/libcore/benches/num/dec2flt/mod.rs
+++ b/src/libcore/benches/num/dec2flt/mod.rs
@@ -1,4 +1,3 @@
-use std::f64;
 use test::Bencher;
 
 #[bench]
diff --git a/src/libcore/benches/num/flt2dec/mod.rs b/src/libcore/benches/num/flt2dec/mod.rs
index b810dd12ab6..a1ce33d0bb4 100644
--- a/src/libcore/benches/num/flt2dec/mod.rs
+++ b/src/libcore/benches/num/flt2dec/mod.rs
@@ -5,7 +5,6 @@ mod strategy {
 
 use core::num::flt2dec::MAX_SIG_DIGITS;
 use core::num::flt2dec::{decode, DecodableFloat, Decoded, FullDecoded};
-use std::f64;
 use std::io::Write;
 use std::vec::Vec;
 use test::Bencher;
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index e0954a661c8..1a1dbcd7b87 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -76,7 +76,6 @@ fn test_cmp_by() {
 #[test]
 fn test_partial_cmp_by() {
     use core::cmp::Ordering;
-    use core::f64;
 
     let f = |x: i32, y: i32| (x * x).partial_cmp(&y);
     let xs = || [1, 2, 3, 4].iter().copied();
@@ -2894,7 +2893,7 @@ fn test_is_sorted() {
     assert!(![1, 3, 2].iter().is_sorted());
     assert!([0].iter().is_sorted());
     assert!(std::iter::empty::<i32>().is_sorted());
-    assert!(![0.0, 1.0, std::f32::NAN].iter().is_sorted());
+    assert!(![0.0, 1.0, f32::NAN].iter().is_sorted());
     assert!([-2, -1, 0, 3].iter().is_sorted());
     assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs()));
     assert!(!["c", "bb", "aaa"].iter().is_sorted());
diff --git a/src/libcore/tests/num/dec2flt/rawfp.rs b/src/libcore/tests/num/dec2flt/rawfp.rs
index 665fb6b9efb..c098b9c2ba2 100644
--- a/src/libcore/tests/num/dec2flt/rawfp.rs
+++ b/src/libcore/tests/num/dec2flt/rawfp.rs
@@ -1,8 +1,6 @@
 use core::num::dec2flt::rawfp::RawFloat;
 use core::num::dec2flt::rawfp::{fp_to_float, next_float, prev_float, round_normal};
 use core::num::diy_float::Fp;
-use std::f32;
-use std::f64;
 
 fn integer_decode(f: f64) -> (u64, i16, i8) {
     RawFloat::integer_decode(f)
diff --git a/src/libcore/tests/num/mod.rs b/src/libcore/tests/num/mod.rs
index f61793a3bca..181bbb8e187 100644
--- a/src/libcore/tests/num/mod.rs
+++ b/src/libcore/tests/num/mod.rs
@@ -205,8 +205,6 @@ test_impl_from! { test_u32f64, u32, f64 }
 // Float -> Float
 #[test]
 fn test_f32f64() {
-    use core::f32;
-
     let max: f64 = f32::MAX.into();
     assert_eq!(max as f32, f32::MAX);
     assert!(max.is_normal());
@@ -704,5 +702,5 @@ macro_rules! test_float {
     };
 }
 
-test_float!(f32, f32, ::core::f32::INFINITY, ::core::f32::NEG_INFINITY, ::core::f32::NAN);
-test_float!(f64, f64, ::core::f64::INFINITY, ::core::f64::NEG_INFINITY, ::core::f64::NAN);
+test_float!(f32, f32, f32::INFINITY, f32::NEG_INFINITY, f32::NAN);
+test_float!(f64, f64, f64::INFINITY, f64::NEG_INFINITY, f64::NAN);
diff --git a/src/libcore/tests/ops.rs b/src/libcore/tests/ops.rs
index 43eb498d26a..3c83f0f2300 100644
--- a/src/libcore/tests/ops.rs
+++ b/src/libcore/tests/ops.rs
@@ -61,25 +61,23 @@ fn test_range_inclusive() {
 
 #[test]
 fn test_range_is_empty() {
-    use core::f32::*;
-
     assert!(!(0.0..10.0).is_empty());
     assert!((-0.0..0.0).is_empty());
     assert!((10.0..0.0).is_empty());
 
-    assert!(!(NEG_INFINITY..INFINITY).is_empty());
-    assert!((EPSILON..NAN).is_empty());
-    assert!((NAN..EPSILON).is_empty());
-    assert!((NAN..NAN).is_empty());
+    assert!(!(f32::NEG_INFINITY..f32::INFINITY).is_empty());
+    assert!((f32::EPSILON..f32::NAN).is_empty());
+    assert!((f32::NAN..f32::EPSILON).is_empty());
+    assert!((f32::NAN..f32::NAN).is_empty());
 
     assert!(!(0.0..=10.0).is_empty());
     assert!(!(-0.0..=0.0).is_empty());
     assert!((10.0..=0.0).is_empty());
 
-    assert!(!(NEG_INFINITY..=INFINITY).is_empty());
-    assert!((EPSILON..=NAN).is_empty());
-    assert!((NAN..=EPSILON).is_empty());
-    assert!((NAN..=NAN).is_empty());
+    assert!(!(f32::NEG_INFINITY..=f32::INFINITY).is_empty());
+    assert!((f32::EPSILON..=f32::NAN).is_empty());
+    assert!((f32::NAN..=f32::EPSILON).is_empty());
+    assert!((f32::NAN..=f32::NAN).is_empty());
 }
 
 #[test]
diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index dbab433e33f..ee8931bf2e7 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -1709,7 +1709,7 @@ fn test_is_sorted() {
     assert!(![1, 3, 2].is_sorted());
     assert!([0].is_sorted());
     assert!(empty.is_sorted());
-    assert!(![0.0, 1.0, std::f32::NAN].is_sorted());
+    assert!(![0.0, 1.0, f32::NAN].is_sorted());
     assert!([-2, -1, 0, 3].is_sorted());
     assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
     assert!(!["c", "bb", "aaa"].is_sorted());
diff --git a/src/libcore/tests/tuple.rs b/src/libcore/tests/tuple.rs
index 3a2914698cc..ea1e281425c 100644
--- a/src/libcore/tests/tuple.rs
+++ b/src/libcore/tests/tuple.rs
@@ -1,5 +1,4 @@
 use std::cmp::Ordering::{Equal, Greater, Less};
-use std::f64::NAN;
 
 #[test]
 fn test_clone() {
@@ -34,12 +33,12 @@ fn test_partial_ord() {
     assert!(big >= small);
     assert!(big >= big);
 
-    assert!(!((1.0f64, 2.0f64) < (NAN, 3.0)));
-    assert!(!((1.0f64, 2.0f64) <= (NAN, 3.0)));
-    assert!(!((1.0f64, 2.0f64) > (NAN, 3.0)));
-    assert!(!((1.0f64, 2.0f64) >= (NAN, 3.0)));
-    assert!(((1.0f64, 2.0f64) < (2.0, NAN)));
-    assert!(!((2.0f64, 2.0f64) < (2.0, NAN)));
+    assert!(!((1.0f64, 2.0f64) < (f64::NAN, 3.0)));
+    assert!(!((1.0f64, 2.0f64) <= (f64::NAN, 3.0)));
+    assert!(!((1.0f64, 2.0f64) > (f64::NAN, 3.0)));
+    assert!(!((1.0f64, 2.0f64) >= (f64::NAN, 3.0)));
+    assert!(((1.0f64, 2.0f64) < (2.0, f64::NAN)));
+    assert!(!((2.0f64, 2.0f64) < (2.0, f64::NAN)));
 }
 
 #[test]