diff --git a/scripts/aux/extractSingleTree.py b/scripts/aux/extractSingleTree.py
index 859364f4be..1ac57bd698 100755
--- a/scripts/aux/extractSingleTree.py
+++ b/scripts/aux/extractSingleTree.py
@@ -62,8 +62,8 @@ def restricted_integer(x):
     if name == "particleIndexStart" or name == "particleIndexCount":
         continue
     print("   "+name)
-    dataset    = fromFile[halosName][name][:]
-    toFile["forestHalos"].create_dataset(name,data=dataset[start[0]:end[0],...])
+    dataset    = fromFile[halosName][name][start[0]:end[0],...]
+    toFile["forestHalos"].create_dataset(name,data=dataset)
 print("...done")
 
 # Create the forestIndex group.