diff --git a/code/libraries/array/java/nu/marginalia/array/page/SegmentLongArray.java b/code/libraries/array/java/nu/marginalia/array/page/SegmentLongArray.java
index 76e2b213..c87b16f0 100644
--- a/code/libraries/array/java/nu/marginalia/array/page/SegmentLongArray.java
+++ b/code/libraries/array/java/nu/marginalia/array/page/SegmentLongArray.java
@@ -183,10 +183,11 @@ public class SegmentLongArray implements LongArray {
             throw new IndexOutOfBoundsException("Destination array too small");
 
         MemorySegment.copy(
-                source.getMemorySegment(), JAVA_LONG, sourceStartL,
-                segment, JAVA_LONG, destStartL,
+                source.getMemorySegment(), JAVA_LONG, sourceStartL * JAVA_LONG.byteSize(),
+                segment, JAVA_LONG, destStartL * JAVA_LONG.byteSize(),
                 destEndL - destStartL
         );
+
     }
 
     @Override
diff --git a/code/libraries/array/java/nu/marginalia/array/page/UnsafeLongArray.java b/code/libraries/array/java/nu/marginalia/array/page/UnsafeLongArray.java
index 36e9f32e..f4c47dd4 100644
--- a/code/libraries/array/java/nu/marginalia/array/page/UnsafeLongArray.java
+++ b/code/libraries/array/java/nu/marginalia/array/page/UnsafeLongArray.java
@@ -284,10 +284,11 @@ public class UnsafeLongArray implements LongArray {
             throw new IndexOutOfBoundsException("Destination array too small");
 
         MemorySegment.copy(
-                source.getMemorySegment(), JAVA_LONG, sourceStartL,
-                segment, JAVA_LONG, destStartL,
+                source.getMemorySegment(), JAVA_LONG, sourceStartL * JAVA_LONG.byteSize(),
+                segment, JAVA_LONG, destStartL * JAVA_LONG.byteSize(),
                 destEndL - destStartL
         );
+
     }
 
 }