diff --git a/units/src/locktime/relative.rs b/units/src/locktime/relative.rs
index a217391da..7a25d4906 100644
--- a/units/src/locktime/relative.rs
+++ b/units/src/locktime/relative.rs
@@ -191,6 +191,9 @@ impl<'a> Arbitrary<'a> for Time {
 
 #[cfg(test)]
 mod tests {
+    #[cfg(feature = "serde")]
+    use internals::serde_round_trip;
+
     use super::*;
 
     const MAXIMUM_ENCODABLE_SECONDS: u32 = u16::MAX as u32 * 512;
@@ -248,4 +251,20 @@ mod tests {
         let result = Time::from_seconds_floor(MAXIMUM_ENCODABLE_SECONDS + 512);
         assert!(result.is_err());
     }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    pub fn encode_decode_height() {
+        serde_round_trip!(Height::ZERO);
+        serde_round_trip!(Height::MIN);
+        serde_round_trip!(Height::MAX);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    pub fn encode_decode_time() {
+        serde_round_trip!(Time::ZERO);
+        serde_round_trip!(Time::MIN);
+        serde_round_trip!(Time::MAX);
+    }
 }