diff --git a/lib/rdf/namespace.ex b/lib/rdf/namespace.ex
index 076a1ad..97b6cce 100644
--- a/lib/rdf/namespace.ex
+++ b/lib/rdf/namespace.ex
@@ -55,8 +55,13 @@ defmodule RDF.Namespace do
   defp do_resolve_term(RDF, term), do: do_resolve_term(RDF.NS.RDF, term)
 
   defp do_resolve_term(namespace, term) do
-    if Code.ensure_compiled?(namespace) and
-        Keyword.has_key?(namespace.__info__(:functions), :__resolve_term__)do
+    is_module =
+      case Code.ensure_compiled(namespace) do
+        {:module, _} -> true
+        _ -> false
+      end
+
+    if is_module and Keyword.has_key?(namespace.__info__(:functions), :__resolve_term__) do
       namespace.__resolve_term__(term)
     else
       raise RDF.Namespace.UndefinedTermError,
diff --git a/lib/rdf/vocabulary_namespace.ex b/lib/rdf/vocabulary_namespace.ex
index b830b90..7bd08ef 100644
--- a/lib/rdf/vocabulary_namespace.ex
+++ b/lib/rdf/vocabulary_namespace.ex
@@ -577,7 +577,10 @@ defmodule RDF.Vocabulary.Namespace do
   @doc false
   @spec vocabulary_namespace?(module) :: boolean
   def vocabulary_namespace?(name) do
-    Code.ensure_compiled?(name) && function_exported?(name, :__base_iri__, 0)
+    case Code.ensure_compiled(name) do
+      {:module, name} -> function_exported?(name, :__base_iri__, 0)
+      _ -> false
+    end
   end
 
 end