diff --git a/lib/rdf/iri.ex b/lib/rdf/iri.ex
index 0c143c4..3d4e5ed 100644
--- a/lib/rdf/iri.ex
+++ b/lib/rdf/iri.ex
@@ -31,7 +31,8 @@ defmodule RDF.IRI do
   """
   def new(iri)
   def new(iri) when is_binary(iri),   do: %RDF.IRI{value: iri}
-  def new(qname) when is_atom(qname), do: Namespace.resolve_term(qname)
+  def new(qname) when is_atom(qname) and not qname in [nil, true, false],
+    do: Namespace.resolve_term(qname)
   def new(%URI{} = uri),              do: uri |> URI.to_string |> new
   def new(%RDF.IRI{} = iri),          do: iri
 
@@ -44,7 +45,8 @@ defmodule RDF.IRI do
   """
   def new!(iri)
   def new!(iri) when is_binary(iri),   do: iri |> valid!() |> new()
-  def new!(qname) when is_atom(qname), do: new(qname)  # since terms of a namespace are already validated
+  def new!(qname) when is_atom(qname) and not qname in [nil, true, false],
+    do: new(qname)  # since terms of a namespace are already validated
   def new!(%URI{} = uri),              do: uri |> valid!() |> new()
   def new!(%RDF.IRI{} = iri),          do: valid!(iri)
 
@@ -90,11 +92,18 @@ defmodule RDF.IRI do
   """
   def absolute?(iri)
 
-  def absolute?(%RDF.IRI{value: value}),    do: absolute?(value)
-  def absolute?(qname) when is_atom(qname), do: Namespace.resolve_term(qname) |> absolute?()
-  def absolute?(%URI{scheme: nil}),         do: false
-  def absolute?(%URI{scheme: _}),           do: true
-  def absolute?(value),                     do: not is_nil(scheme(value))
+  def absolute?(value) when is_binary(value), do: not is_nil(scheme(value))
+  def absolute?(%RDF.IRI{value: value}),      do: absolute?(value)
+  def absolute?(%URI{scheme: nil}),           do: false
+  def absolute?(%URI{scheme: _}),             do: true
+  def absolute?(qname) when is_atom(qname) and not qname in [nil, true, false] do
+    try do
+      qname |> Namespace.resolve_term |> absolute?()
+    rescue
+      _ -> false
+    end
+  end
+  def absolute?(_), do: false
 
 
   @doc """
@@ -157,7 +166,11 @@ defmodule RDF.IRI do
       iex> RDF.IRI.scheme("not an iri")
       nil
   """
-  def scheme(iri) do
+  def scheme(iri)
+  def scheme(%RDF.IRI{value: value}),    do: scheme(value)
+  def scheme(%URI{scheme: scheme}),      do: scheme
+  def scheme(qname) when is_atom(qname), do: Namespace.resolve_term(qname) |> scheme()
+  def scheme(iri) when is_binary(iri) do
     with [_, scheme] <- Regex.run(@scheme_regex, iri) do
       scheme
     end
@@ -169,7 +182,8 @@ defmodule RDF.IRI do
   """
   def parse(iri)
   def parse(iri) when is_binary(iri),   do: URI.parse(iri) |> empty_fragment_shim(iri)
-  def parse(qname) when is_atom(qname), do: Namespace.resolve_term(qname) |> parse()
+  def parse(qname) when is_atom(qname) and not qname in [nil, true, false],
+    do: Namespace.resolve_term(qname) |> parse()
   def parse(%RDF.IRI{value: value}),    do: URI.parse(value) |> empty_fragment_shim(value)
   def parse(%URI{} = uri),              do: uri
 
diff --git a/test/unit/iri_test.exs b/test/unit/iri_test.exs
index ded8bd9..86881ea 100644
--- a/test/unit/iri_test.exs
+++ b/test/unit/iri_test.exs
@@ -53,6 +53,16 @@ defmodule RDF.IRITest do
     test "with a resolvable atom" do
       assert IRI.new(EX.Foo) == %IRI{value: "http://example.com/#Foo"}
     end
+
+    test "with a non-resolvable atom" do
+      assert_raise RDF.Namespace.UndefinedTermError, fn -> IRI.new(Foo.Bar) end
+    end
+
+    test "with Elixirs special atoms" do
+      assert_raise FunctionClauseError, fn -> IRI.new(true) end
+      assert_raise FunctionClauseError, fn -> IRI.new(false) end
+      assert_raise FunctionClauseError, fn -> IRI.new(nil) end
+    end
   end
 
 
@@ -83,6 +93,16 @@ defmodule RDF.IRITest do
         end
       end)
     end
+
+    test "with a non-resolvable atom" do
+      assert_raise RDF.Namespace.UndefinedTermError, fn -> IRI.new!(Foo.Bar) end
+    end
+
+    test "with Elixirs special atoms" do
+      assert_raise FunctionClauseError, fn -> IRI.new!(true) end
+      assert_raise FunctionClauseError, fn -> IRI.new!(false) end
+      assert_raise FunctionClauseError, fn -> IRI.new!(nil) end
+    end
   end
 
 
@@ -97,6 +117,13 @@ defmodule RDF.IRITest do
       assert IRI.valid!(EX.Foo) == EX.Foo
     end
 
+    test "with a non-resolvable atom" do
+      assert_raise RDF.IRI.InvalidError, fn -> IRI.valid!(true) == false end
+      assert_raise RDF.IRI.InvalidError, fn -> IRI.valid!(false) == false end
+      assert_raise RDF.IRI.InvalidError, fn -> IRI.valid!(nil) == false end
+      assert_raise RDF.IRI.InvalidError, fn -> IRI.valid!(Foo.Bar) == false end
+    end
+
     test "with relative iris" do
       Enum.each(relative_iris(), fn relative_iri ->
         assert_raise RDF.IRI.InvalidError, fn ->
@@ -127,6 +154,13 @@ defmodule RDF.IRITest do
       assert IRI.valid?(EX.Foo) == true
     end
 
+    test "with a non-resolvable atom" do
+      assert IRI.valid?(true) == false
+      assert IRI.valid?(false) == false
+      assert IRI.valid?(nil) == false
+      assert IRI.valid?(Foo.Bar) == false
+    end
+
     test "with relative iris" do
       Enum.each(relative_iris(), fn relative_iri ->
         assert IRI.valid?(relative_iri) == false
@@ -153,6 +187,13 @@ defmodule RDF.IRITest do
       assert IRI.absolute?(EX.Foo) == true
     end
 
+    test "with a non-resolvable atom" do
+      assert IRI.absolute?(true) == false
+      assert IRI.absolute?(false) == false
+      assert IRI.absolute?(nil) == false
+      assert IRI.absolute?(Foo.Bar) == false
+    end
+
     test "with relative iris" do
       Enum.each(relative_iris(), fn relative_iri ->
         assert IRI.absolute?(relative_iri) == false
@@ -258,6 +299,12 @@ defmodule RDF.IRITest do
         refute IRI.parse(invalid_iri)
       end)
     end
+
+    test "with Elixirs special atoms" do
+      assert_raise FunctionClauseError, fn -> IRI.parse(true) end
+      assert_raise FunctionClauseError, fn -> IRI.parse(false) end
+      assert_raise FunctionClauseError, fn -> IRI.parse(nil) end
+    end
   end