diff --git a/src/main/java/gov/usgs/earthquake/nshmp/data/Sequences.java b/src/main/java/gov/usgs/earthquake/nshmp/data/Sequences.java
index 9d6d24add071bdf43440daa9800ba140f72052b4..e9eae04f41ab3acfc689a151e282d54d34c6b486 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/data/Sequences.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/data/Sequences.java
@@ -102,7 +102,7 @@ class Sequences {
     var combinedMap = xySequences.stream()
         .flatMap(XySequence::stream)
         .collect(Collectors.toMap(
-            (XyPoint xy) -> (double) xy.x(),
+            XyPoint::x,
             (XyPoint xy) -> (double) xy.y(),
             (a, b) -> a + b,
             TreeMap::new));