diff --git a/src/main/java/pythagoras/d/Vector.java b/src/main/java/pythagoras/d/Vector.java
index 7e35290..751ee46 100644
--- a/src/main/java/pythagoras/d/Vector.java
+++ b/src/main/java/pythagoras/d/Vector.java
@@ -21,7 +21,7 @@ public class Vector extends AbstractVector
     }
 
     /** Creates a vector equal to {@code other}. */
-    public Vector (IVector other) {
+    public Vector (XY other) {
         set(other);
     }
 
diff --git a/src/main/java/pythagoras/f/Vector.java b/src/main/java/pythagoras/f/Vector.java
index 698b80c..5861a9a 100644
--- a/src/main/java/pythagoras/f/Vector.java
+++ b/src/main/java/pythagoras/f/Vector.java
@@ -21,7 +21,7 @@ public class Vector extends AbstractVector
     }
 
     /** Creates a vector equal to {@code other}. */
-    public Vector (IVector other) {
+    public Vector (XY other) {
         set(other);
     }