diff --git a/library/core/tests/num/mod.rs b/library/core/tests/num/mod.rs
index 378c8af344b59..190528fd445bf 100644
--- a/library/core/tests/num/mod.rs
+++ b/library/core/tests/num/mod.rs
@@ -27,6 +27,8 @@ mod bignum;
 mod dec2flt;
 mod flt2dec;
 
+mod nan;
+
 /// Adds the attribute to all items in the block.
 macro_rules! cfg_block {
     ($(#[$attr:meta]{$($it:item)*})*) => {$($(
diff --git a/src/test/ui/format-nan.rs b/library/core/tests/num/nan.rs
similarity index 78%
rename from src/test/ui/format-nan.rs
rename to library/core/tests/num/nan.rs
index e4a134fa2fbe0..011ffa790beee 100644
--- a/src/test/ui/format-nan.rs
+++ b/library/core/tests/num/nan.rs
@@ -1,7 +1,6 @@
-// run-pass
-
-pub fn main() {
-    use std::f64;
+#[test]
+fn test_nan() {
+    use core::f64;
     let x = "NaN".to_string();
     assert_eq!(format!("{}", f64::NAN), x);
     assert_eq!(format!("{:e}", f64::NAN), x);