diff --git a/lib/rdf/prefix_map.ex b/lib/rdf/prefix_map.ex
index c329605..69c6346 100644
--- a/lib/rdf/prefix_map.ex
+++ b/lib/rdf/prefix_map.ex
@@ -412,7 +412,7 @@ defmodule RDF.PrefixMap do
 
     def member?(%RDF.PrefixMap{map: map}, mapping), do: Enumerable.member?(map, mapping)
     def count(%RDF.PrefixMap{map: map}), do: Enumerable.count(map)
-    def slice(_prefix_map), do: {:error, __MODULE__}
+    def slice(%RDF.PrefixMap{map: map}), do: Enumerable.slice(map)
   end
 
   defimpl Inspect do
diff --git a/lib/rdf/property_map.ex b/lib/rdf/property_map.ex
index 4f11840..a0cb790 100644
--- a/lib/rdf/property_map.ex
+++ b/lib/rdf/property_map.ex
@@ -312,7 +312,7 @@ defmodule RDF.PropertyMap do
 
     def member?(%PropertyMap{iris: iris}, mapping), do: Enumerable.member?(iris, mapping)
     def count(%PropertyMap{iris: iris}), do: Enumerable.count(iris)
-    def slice(_property_map), do: {:error, __MODULE__}
+    def slice(%PropertyMap{iris: iris}), do: Enumerable.slice(iris)
   end
 
   defimpl Inspect do