diff --git a/tests/test_de.rs b/tests/test_de.rs
index 44d10476..7c760872 100644
--- a/tests/test_de.rs
+++ b/tests/test_de.rs
@@ -450,6 +450,13 @@ fn test_numbers() {
     }
 }
 
+#[test]
+fn test_nan() {
+    // There is no negative NaN in YAML.
+    assert!(serde_yaml::from_str::<f32>(".nan").unwrap().is_sign_positive());
+    assert!(serde_yaml::from_str::<f64>(".nan").unwrap().is_sign_positive());
+}
+
 #[test]
 fn test_stateful() {
     struct Seed(i64);