diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py
index ea00a8b99..8f8288f88 100644
--- a/Lib/test/test_float.py
+++ b/Lib/test/test_float.py
@@ -1024,8 +1024,6 @@ class InfNanTest(unittest.TestCase):
         self.assertEqual(str(1e300 * 1e300), "inf")
         self.assertEqual(str(-1e300 * 1e300), "-inf")
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_nan_from_str(self):
         self.assertTrue(isnan(float("nan")))
         self.assertTrue(isnan(float("+nan")))
@@ -1055,8 +1053,6 @@ class InfNanTest(unittest.TestCase):
         self.assertRaises(ValueError, float, "+-NaN")
         self.assertRaises(ValueError, float, "--nAn")
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_nan_as_str(self):
         self.assertEqual(repr(1e300 * 1e300 * 0), "nan")
         self.assertEqual(repr(-1e300 * 1e300 * 0), "nan")
diff --git a/common/src/float_ops.rs b/common/src/float_ops.rs
index 528707668..f4d8b032f 100644
--- a/common/src/float_ops.rs
+++ b/common/src/float_ops.rs
@@ -226,7 +226,9 @@ pub fn to_string(value: f64) -> String {
             format!("{}e{:+#03}", significand, exponent)
         }
     } else {
-        value.to_string()
+        let mut s = value.to_string();
+        s.make_ascii_lowercase();
+        s
     }
 }