diff --git a/modules/product/src/main/java/com/opengamma/strata/product/swap/Swap.java b/modules/product/src/main/java/com/opengamma/strata/product/swap/Swap.java
index 76830b13fe..300b3c16e7 100644
--- a/modules/product/src/main/java/com/opengamma/strata/product/swap/Swap.java
+++ b/modules/product/src/main/java/com/opengamma/strata/product/swap/Swap.java
@@ -88,7 +88,7 @@ public static Swap of(SwapLeg... legs) {
    * @param legs  the list of legs
    * @return the swap
    */
-  public static Swap of(List<SwapLeg> legs) {
+  public static Swap of(List<? extends SwapLeg> legs) {
     ArgChecker.notEmpty(legs, "legs");
     return new Swap(ImmutableList.copyOf(legs));
   }