diff --git a/lib/rdf/dataset.ex b/lib/rdf/dataset.ex
index de5052f..fd7e855 100644
--- a/lib/rdf/dataset.ex
+++ b/lib/rdf/dataset.ex
@@ -403,6 +403,7 @@ defmodule RDF.Dataset do
       iex> RDF.Dataset.fetch(dataset, EX.Foo)
       :error
   """
+  @impl Access
   def fetch(%RDF.Dataset{graphs: graphs}, graph_name) do
     Access.fetch(graphs, coerce_graph_name(graph_name))
   end
@@ -473,6 +474,7 @@ defmodule RDF.Dataset do
       ...>   end)
       {RDF.Graph.new(EX.Graph, {EX.S, EX.P, EX.O}), RDF.Dataset.new({EX.S, EX.P, EX.NEW, EX.Graph})}
   """
+  @impl Access
   def get_and_update(%RDF.Dataset{} = dataset, graph_name, fun) do
     with graph_context = coerce_graph_name(graph_name) do
       case fun.(get(dataset, graph_context)) do
@@ -522,6 +524,7 @@ defmodule RDF.Dataset do
       iex> RDF.Dataset.pop(dataset, EX.Foo)
       {nil, dataset}
   """
+  @impl Access
   def pop(%RDF.Dataset{name: name, graphs: graphs} = dataset, graph_name) do
     case Access.pop(graphs, coerce_graph_name(graph_name)) do
       {nil, _} ->
diff --git a/lib/rdf/datatype.ex b/lib/rdf/datatype.ex
index f3b844c..27bc40d 100644
--- a/lib/rdf/datatype.ex
+++ b/lib/rdf/datatype.ex
@@ -125,6 +125,7 @@ defmodule RDF.Datatype do
       alias RDF.Datatype.NS.XSD
 
       @id unquote(id)
+      @impl unquote(__MODULE__)
       def id, do: @id
 
 
@@ -182,6 +183,9 @@ defmodule RDF.Datatype do
       def convert(value, _), do: nil
 
 
+      @impl unquote(__MODULE__)
+      def lexical(literal)
+
       def lexical(%RDF.Literal{value: value, uncanonical_lexical: nil}) do
         canonical_lexical(value)
       end
@@ -191,21 +195,30 @@ defmodule RDF.Datatype do
       end
 
 
+      @impl unquote(__MODULE__)
       def canonical_lexical(value), do: to_string(value)
 
+      @impl unquote(__MODULE__)
       def invalid_lexical(value), do: to_string(value)
 
+      @impl unquote(__MODULE__)
+      def canonical(literal)
       def canonical(%Literal{value:               nil} = literal), do: literal
       def canonical(%Literal{uncanonical_lexical: nil} = literal), do: literal
       def canonical(%Literal{} = literal) do
         %Literal{literal | uncanonical_lexical: nil}
       end
 
+      @impl unquote(__MODULE__)
+      def valid?(literal)
       def valid?(%Literal{value: nil}),    do: false
       def valid?(%Literal{datatype: @id}), do: true
       def valid?(_), do: false
 
 
+      @impl unquote(__MODULE__)
+      def equal_value?(literal1, literal2)
+
       def equal_value?(%Literal{uncanonical_lexical: lexical1, datatype: @id, value: nil},
                        %Literal{uncanonical_lexical: lexical2, datatype: @id}) do
         lexical1 == lexical2
diff --git a/lib/rdf/datatypes/boolean.ex b/lib/rdf/datatypes/boolean.ex
index 0b150c5..e28415f 100644
--- a/lib/rdf/datatypes/boolean.ex
+++ b/lib/rdf/datatypes/boolean.ex
@@ -8,6 +8,9 @@ defmodule RDF.Boolean do
   import RDF.Literal.Guards
 
 
+  @impl RDF.Datatype
+  def convert(value, opts)
+
   def convert(value, _) when is_boolean(value), do: value
 
   def convert(value, opts) when is_binary(value) do
@@ -27,6 +30,9 @@ defmodule RDF.Boolean do
   def convert(value, opts), do: super(value, opts)
 
 
+  @impl RDF.Datatype
+  def cast(literal)
+
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
       not RDF.Literal.valid?(literal) ->
diff --git a/lib/rdf/datatypes/date.ex b/lib/rdf/datatypes/date.ex
index 7fcc07c..e36c40d 100644
--- a/lib/rdf/datatypes/date.ex
+++ b/lib/rdf/datatypes/date.ex
@@ -10,6 +10,9 @@ defmodule RDF.Date do
   @grammar ~r/\A(-?\d{4}-\d{2}-\d{2})((?:[\+\-]\d{2}:\d{2})|UTC|GMT|Z)?\Z/
 
 
+  @impl RDF.Datatype
+  def convert(value, opts)
+
   def convert(%Date{} = value, %{tz: "+00:00"} = opts) do
     {convert(value, Map.delete(opts, :tz)), "Z"}
   end
@@ -47,6 +50,9 @@ defmodule RDF.Date do
   end
 
 
+  @impl RDF.Datatype
+  def canonical_lexical(value)
+
   def canonical_lexical(%Date{} = value) do
     Date.to_iso8601(value)
   end
@@ -56,6 +62,9 @@ defmodule RDF.Date do
   end
 
 
+  @impl RDF.Datatype
+  def cast(literal)
+
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
       not RDF.Literal.valid?(literal) ->
diff --git a/lib/rdf/datatypes/date_time.ex b/lib/rdf/datatypes/date_time.ex
index b1f28a7..953f6e8 100644
--- a/lib/rdf/datatypes/date_time.ex
+++ b/lib/rdf/datatypes/date_time.ex
@@ -8,9 +8,8 @@ defmodule RDF.DateTime do
   import RDF.Literal.Guards
 
 
-  def now() do
-    new(DateTime.utc_now())
-  end
+  @impl RDF.Datatype
+  def convert(value, opts)
 
   # Special case for date and dateTime, for which 0 is not a valid year
   def convert(%DateTime{year: 0} = value, opts), do: super(value, opts)
@@ -52,6 +51,9 @@ defmodule RDF.DateTime do
   def convert(value, opts), do: super(value, opts)
 
 
+  @impl RDF.Datatype
+  def canonical_lexical(value)
+
   def canonical_lexical(%DateTime{} = value) do
     DateTime.to_iso8601(value)
   end
@@ -61,6 +63,9 @@ defmodule RDF.DateTime do
   end
 
 
+  @impl RDF.Datatype
+  def cast(literal)
+
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
       not RDF.Literal.valid?(literal) ->
@@ -91,6 +96,19 @@ defmodule RDF.DateTime do
   def cast(_), do: nil
 
 
+  @doc """
+  Builds a `RDF.DateTime` literal for current moment in time.
+  """
+  def now() do
+    new(DateTime.utc_now())
+  end
+
+
+  @doc """
+  Extracts the timezone string from a `RDF.DateTime` literal.
+  """
+  def tz(literal)
+
   def tz(%Literal{value: %NaiveDateTime{}}), do: ""
 
   def tz(date_time_literal) do
@@ -101,6 +119,7 @@ defmodule RDF.DateTime do
     end
   end
 
+
   @doc """
   Converts a datetime literal to a canonical string, preserving the zone information.
   """
diff --git a/lib/rdf/datatypes/decimal.ex b/lib/rdf/datatypes/decimal.ex
index 22f9ca3..87416cb 100644
--- a/lib/rdf/datatypes/decimal.ex
+++ b/lib/rdf/datatypes/decimal.ex
@@ -9,6 +9,9 @@ defmodule RDF.Decimal do
   alias Elixir.Decimal, as: D
 
 
+  @impl RDF.Datatype
+  def convert(value, opts)
+
   def convert(%D{coef: coef} = value, opts) when coef in ~w[qNaN sNaN inf]a,
     do: super(value, opts)
 
@@ -35,6 +38,9 @@ defmodule RDF.Decimal do
   def convert(value, opts), do: super(value, opts)
 
 
+  @impl RDF.Datatype
+  def canonical_lexical(value)
+
   def canonical_lexical(%D{sign: sign, coef: :qNaN}),
     do: if sign == 1, do: "NaN", else: "-NaN"
 
@@ -66,6 +72,8 @@ defmodule RDF.Decimal do
     do: canonical_decimal(%{decimal | coef: Kernel.div(coef, 10), exp: exp + 1})
 
 
+  @impl RDF.Datatype
+  def cast(literal)
 
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
@@ -99,6 +107,7 @@ defmodule RDF.Decimal do
   def cast(_), do: nil
 
 
+  @impl RDF.Datatype
   def equal_value?(left, right), do: RDF.Numeric.equal_value?(left, right)
 
 end
diff --git a/lib/rdf/datatypes/double.ex b/lib/rdf/datatypes/double.ex
index 516a889..9a07ada 100644
--- a/lib/rdf/datatypes/double.ex
+++ b/lib/rdf/datatypes/double.ex
@@ -19,6 +19,8 @@ defmodule RDF.Double do
     end
   end
 
+  @impl RDF.Datatype
+  def convert(value, opts)
 
   def convert(value, _) when is_float(value),   do: value
 
@@ -53,6 +55,9 @@ defmodule RDF.Double do
   def convert(value, opts), do: super(value, opts)
 
 
+  @impl RDF.Datatype
+  def canonical_lexical(value)
+
   def canonical_lexical(:nan),                       do: "NaN"
   def canonical_lexical(:positive_infinity),         do: "INF"
   def canonical_lexical(:negative_infinity),         do: "-INF"
@@ -94,6 +99,8 @@ defmodule RDF.Double do
   end
 
 
+  @impl RDF.Datatype
+  def cast(literal)
 
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
@@ -131,6 +138,7 @@ defmodule RDF.Double do
   def cast(_), do: nil
 
 
+  @impl RDF.Datatype
   def equal_value?(left, right), do: RDF.Numeric.equal_value?(left, right)
 
 end
diff --git a/lib/rdf/datatypes/integer.ex b/lib/rdf/datatypes/integer.ex
index e5bb870..476fb97 100644
--- a/lib/rdf/datatypes/integer.ex
+++ b/lib/rdf/datatypes/integer.ex
@@ -8,6 +8,9 @@ defmodule RDF.Integer do
   import RDF.Literal.Guards
 
 
+  @impl RDF.Datatype
+  def convert(value, opts)
+
   def convert(value, _) when is_integer(value), do: value
 
   def convert(value, opts) when is_binary(value) do
@@ -21,6 +24,9 @@ defmodule RDF.Integer do
   def convert(value, opts), do: super(value, opts)
 
 
+  @impl RDF.Datatype
+  def cast(literal)
+
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
       not RDF.Literal.valid?(literal) ->
@@ -61,6 +67,7 @@ defmodule RDF.Integer do
   def cast(_), do: nil
 
 
+  @impl RDF.Datatype
   def equal_value?(left, right), do: RDF.Numeric.equal_value?(left, right)
 
 end
diff --git a/lib/rdf/datatypes/lang_string.ex b/lib/rdf/datatypes/lang_string.ex
index afd907e..de987e9 100644
--- a/lib/rdf/datatypes/lang_string.ex
+++ b/lib/rdf/datatypes/lang_string.ex
@@ -16,13 +16,22 @@ defmodule RDF.LangString do
   end
 
 
+  @impl RDF.Datatype
   def convert(value, _), do: to_string(value)
 
 
+  @impl RDF.Datatype
+  def valid?(literal)
   def valid?(%Literal{language: nil}), do: false
   def valid?(literal), do: super(literal)
 
 
+  @impl RDF.Datatype
+  def cast(_) do
+    nil
+  end
+
+
   @doc """
   Checks if a language tagged string literal or language tag matches a language range.
 
@@ -53,9 +62,4 @@ defmodule RDF.LangString do
     end
   end
 
-
-  def cast(_) do
-    nil
-  end
-
 end
diff --git a/lib/rdf/datatypes/string.ex b/lib/rdf/datatypes/string.ex
index 3d21400..3b87fbe 100644
--- a/lib/rdf/datatypes/string.ex
+++ b/lib/rdf/datatypes/string.ex
@@ -28,9 +28,13 @@ defmodule RDF.String do
   end
 
 
+  @impl RDF.Datatype
   def convert(value, _), do: to_string(value)
 
 
+  @impl RDF.Datatype
+  def cast(literal)
+
   def cast(%RDF.IRI{value: value}), do: new(value)
 
   def cast(%RDF.Literal{datatype: datatype} = literal) do
diff --git a/lib/rdf/datatypes/time.ex b/lib/rdf/datatypes/time.ex
index c445d1c..3f8c334 100644
--- a/lib/rdf/datatypes/time.ex
+++ b/lib/rdf/datatypes/time.ex
@@ -11,6 +11,9 @@ defmodule RDF.Time do
   @tz_grammar ~r/\A(?:([\+\-])(\d{2}):(\d{2}))\Z/
 
 
+  @impl RDF.Datatype
+  def convert(value, opts)
+
   def convert(%Time{} = value, %{tz: tz} = opts) do
     {convert(value, Map.delete(opts, :tz)), tz}
   end
@@ -62,6 +65,9 @@ defmodule RDF.Time do
   end
 
 
+  @impl RDF.Datatype
+  def canonical_lexical(value)
+
   def canonical_lexical(%Time{} = value) do
     Time.to_iso8601(value)
   end
@@ -70,36 +76,9 @@ defmodule RDF.Time do
     canonical_lexical(value) <> "Z"
   end
 
-  def tz(time_literal) do
-    if valid?(time_literal) do
-      time_literal
-      |> lexical()
-      |> RDF.DateTimeUtils.tz()
-    end
-  end
 
-
-  @doc """
-  Converts a time literal to a canonical string, preserving the zone information.
-  """
-  def canonical_lexical_with_zone(%Literal{datatype: datatype} = literal)
-      when is_xsd_time(datatype) do
-    case tz(literal) do
-      nil ->
-        nil
-
-      zone when zone in ["Z", "", "+00:00"] ->
-        canonical_lexical(literal.value)
-
-      zone ->
-        literal
-        |> lexical()
-        |> String.replace_trailing(zone, "")
-        |> Time.from_iso8601!()
-        |> canonical_lexical()
-        |> Kernel.<>(zone)
-    end
-  end
+  @impl RDF.Datatype
+  def cast(literal)
 
   def cast(%RDF.Literal{datatype: datatype} = literal) do
     cond do
@@ -135,4 +114,39 @@ defmodule RDF.Time do
 
   def cast(_), do: nil
 
+
+  @doc """
+  Extracts the timezone string from a `RDF.Time` literal.
+  """
+  def tz(time_literal) do
+    if valid?(time_literal) do
+      time_literal
+      |> lexical()
+      |> RDF.DateTimeUtils.tz()
+    end
+  end
+
+
+  @doc """
+  Converts a time literal to a canonical string, preserving the zone information.
+  """
+  def canonical_lexical_with_zone(%Literal{datatype: datatype} = literal)
+      when is_xsd_time(datatype) do
+    case tz(literal) do
+      nil ->
+        nil
+
+      zone when zone in ["Z", "", "+00:00"] ->
+        canonical_lexical(literal.value)
+
+      zone ->
+        literal
+        |> lexical()
+        |> String.replace_trailing(zone, "")
+        |> Time.from_iso8601!()
+        |> canonical_lexical()
+        |> Kernel.<>(zone)
+    end
+  end
+
 end
diff --git a/lib/rdf/description.ex b/lib/rdf/description.ex
index 3f1adc6..e93f3b9 100644
--- a/lib/rdf/description.ex
+++ b/lib/rdf/description.ex
@@ -321,6 +321,7 @@ defmodule RDF.Description do
       iex> RDF.Description.fetch(RDF.Description.new(EX.S), EX.foo)
       :error
   """
+  @impl Access
   def fetch(%RDF.Description{predications: predications}, predicate) do
     with {:ok, objects} <- Access.fetch(predications, coerce_predicate(predicate)) do
       {:ok, Map.keys(objects)}
@@ -391,6 +392,7 @@ defmodule RDF.Description do
       ...>   RDF.Description.get_and_update(EX.P1, fn _ -> :pop end)
       {[RDF.iri(EX.O1)], RDF.Description.new({EX.S, EX.P2, EX.O2})}
   """
+  @impl Access
   def get_and_update(description = %RDF.Description{}, predicate, fun) do
     with triple_predicate = coerce_predicate(predicate) do
       case fun.(get(description, triple_predicate)) do
@@ -435,6 +437,7 @@ defmodule RDF.Description do
       iex> RDF.Description.pop(RDF.Description.new({EX.S, EX.P, EX.O}), EX.Missing)
       {nil, RDF.Description.new({EX.S, EX.P, EX.O})}
   """
+  @impl Access
   def pop(description = %RDF.Description{subject: subject, predications: predications}, predicate) do
     case Access.pop(predications, coerce_predicate(predicate)) do
       {nil, _} ->
diff --git a/lib/rdf/graph.ex b/lib/rdf/graph.ex
index 8d6a1dc..d8ab417 100644
--- a/lib/rdf/graph.ex
+++ b/lib/rdf/graph.ex
@@ -319,6 +319,7 @@ defmodule RDF.Graph do
       iex> RDF.Graph.fetch(RDF.Graph.new, EX.foo)
       :error
   """
+  @impl Access
   def fetch(%RDF.Graph{descriptions: descriptions}, subject) do
     Access.fetch(descriptions, coerce_subject(subject))
   end
@@ -380,6 +381,7 @@ defmodule RDF.Graph do
       ...>   end)
       {RDF.Description.new(EX.S, EX.P, EX.O), RDF.Graph.new(EX.S, EX.P, EX.NEW)}
   """
+  @impl Access
   def get_and_update(%RDF.Graph{} = graph, subject, fun) do
     with subject = coerce_subject(subject) do
       case fun.(get(graph, subject)) do
@@ -426,6 +428,7 @@ defmodule RDF.Graph do
       iex> RDF.Graph.pop(RDF.Graph.new({EX.S, EX.P, EX.O}), EX.Missing)
       {nil, RDF.Graph.new({EX.S, EX.P, EX.O})}
   """
+  @impl Access
   def pop(%RDF.Graph{name: name, descriptions: descriptions} = graph, subject) do
     case Access.pop(descriptions, coerce_subject(subject)) do
       {nil, _} ->
diff --git a/lib/rdf/serialization/decoder.ex b/lib/rdf/serialization/decoder.ex
index 3f68a56..404eca5 100644
--- a/lib/rdf/serialization/decoder.ex
+++ b/lib/rdf/serialization/decoder.ex
@@ -28,6 +28,7 @@ defmodule RDF.Serialization.Decoder do
     quote bind_quoted: [], unquote: true do
       @behaviour unquote(__MODULE__)
 
+      @impl unquote(__MODULE__)
       def decode!(content, opts \\ []) do
         case decode(content, opts) do
           {:ok,    data}   -> data
diff --git a/lib/rdf/serialization/encoder.ex b/lib/rdf/serialization/encoder.ex
index 8b6ce90..4b5e02f 100644
--- a/lib/rdf/serialization/encoder.ex
+++ b/lib/rdf/serialization/encoder.ex
@@ -30,6 +30,7 @@ defmodule RDF.Serialization.Encoder do
 
       import RDF.Literal.Guards
 
+      @impl unquote(__MODULE__)
       def encode!(data, opts \\ []) do
         case encode(data, opts) do
           {:ok,    data}   -> data
diff --git a/lib/rdf/serialization/format.ex b/lib/rdf/serialization/format.ex
index 5abe639..7b7c504 100644
--- a/lib/rdf/serialization/format.ex
+++ b/lib/rdf/serialization/format.ex
@@ -71,9 +71,13 @@ defmodule RDF.Serialization.Format do
       @decoder __MODULE__.Decoder
       @encoder __MODULE__.Encoder
 
+      @impl unquote(__MODULE__)
       def decoder, do: @decoder
+
+      @impl unquote(__MODULE__)
       def encoder, do: @encoder
 
+      @impl unquote(__MODULE__)
       def options, do: %{}
 
       defoverridable [decoder: 0, encoder: 0, options: 0]
@@ -104,18 +108,22 @@ defmodule RDF.Serialization.Format do
     quote do
       if !Module.defines?(__MODULE__, {:id, 0}) &&
           Module.get_attribute(__MODULE__, :id) do
+        @impl unquote(__MODULE__)
         def id, do: @id
       end
       if !Module.defines?(__MODULE__, {:name, 0}) &&
           Module.get_attribute(__MODULE__, :name) do
+        @impl unquote(__MODULE__)
         def name, do: @name
       end
       if !Module.defines?(__MODULE__, {:extension, 0}) &&
           Module.get_attribute(__MODULE__, :extension) do
+        @impl unquote(__MODULE__)
         def extension, do: @extension
       end
       if !Module.defines?(__MODULE__, {:media_type, 0}) &&
           Module.get_attribute(__MODULE__, :media_type) do
+        @impl unquote(__MODULE__)
         def media_type, do: @media_type
       end
     end
diff --git a/lib/rdf/serializations/nquads_decoder.ex b/lib/rdf/serializations/nquads_decoder.ex
index 2d5f678..36aa4d4 100644
--- a/lib/rdf/serializations/nquads_decoder.ex
+++ b/lib/rdf/serializations/nquads_decoder.ex
@@ -3,6 +3,7 @@ defmodule RDF.NQuads.Decoder do
 
   use RDF.Serialization.Decoder
 
+  @impl RDF.Serialization.Decoder
   def decode(content, _opts \\ []) do
     with {:ok, tokens, _} <- tokenize(content),
          {:ok, ast}       <- parse(tokens) do
diff --git a/lib/rdf/serializations/nquads_encoder.ex b/lib/rdf/serializations/nquads_encoder.ex
index e257c36..062fbfc 100644
--- a/lib/rdf/serializations/nquads_encoder.ex
+++ b/lib/rdf/serializations/nquads_encoder.ex
@@ -3,6 +3,7 @@ defmodule RDF.NQuads.Encoder do
 
   use RDF.Serialization.Encoder
 
+  @impl RDF.Serialization.Encoder
   def encode(data, _opts \\ []) do
     result =
       data
diff --git a/lib/rdf/serializations/ntriples_decoder.ex b/lib/rdf/serializations/ntriples_decoder.ex
index 1d8c67c..b997ce6 100644
--- a/lib/rdf/serializations/ntriples_decoder.ex
+++ b/lib/rdf/serializations/ntriples_decoder.ex
@@ -3,6 +3,7 @@ defmodule RDF.NTriples.Decoder do
 
   use RDF.Serialization.Decoder
 
+  @impl RDF.Serialization.Decoder
   def decode(content, _opts \\ []) do
     with {:ok, tokens, _} <- tokenize(content),
          {:ok, ast}       <- parse(tokens) do
diff --git a/lib/rdf/serializations/ntriples_encoder.ex b/lib/rdf/serializations/ntriples_encoder.ex
index e079245..0d77f04 100644
--- a/lib/rdf/serializations/ntriples_encoder.ex
+++ b/lib/rdf/serializations/ntriples_encoder.ex
@@ -6,6 +6,7 @@ defmodule RDF.NTriples.Encoder do
   alias RDF.{IRI, Literal, BlankNode}
 
 
+  @impl RDF.Serialization.Encoder
   def encode(data, _opts \\ []) do
     result =
       data
diff --git a/lib/rdf/serializations/turtle_decoder.ex b/lib/rdf/serializations/turtle_decoder.ex
index 07b5567..cfabde9 100644
--- a/lib/rdf/serializations/turtle_decoder.ex
+++ b/lib/rdf/serializations/turtle_decoder.ex
@@ -22,6 +22,7 @@ defmodule RDF.Turtle.Decoder do
     end
   end
 
+  @impl RDF.Serialization.Decoder
   def decode(content, opts \\ %{})
 
   def decode(content, opts) when is_list(opts),
diff --git a/lib/rdf/serializations/turtle_encoder.ex b/lib/rdf/serializations/turtle_encoder.ex
index b0c29f2..3dc49a2 100644
--- a/lib/rdf/serializations/turtle_encoder.ex
+++ b/lib/rdf/serializations/turtle_encoder.ex
@@ -26,6 +26,7 @@ defmodule RDF.Turtle.Encoder do
   @ordered_properties MapSet.new(@predicate_order)
 
 
+  @impl RDF.Serialization.Encoder
   def encode(data, opts \\ []) do
     with base         = Keyword.get(opts, :base) |> init_base(),
          prefixes     = Keyword.get(opts, :prefixes, %{}) |> init_prefixes(),
diff --git a/lib/rdf/vocabulary_namespace.ex b/lib/rdf/vocabulary_namespace.ex
index e766540..a939f3e 100644
--- a/lib/rdf/vocabulary_namespace.ex
+++ b/lib/rdf/vocabulary_namespace.ex
@@ -66,6 +66,7 @@ defmodule RDF.Vocabulary.Namespace do
         def __strict__, do: @strict
 
         @terms unquote(Macro.escape(terms))
+        @impl Elixir.RDF.Namespace
         def __terms__, do: @terms |> Map.keys
 
         @ignored_terms unquote(Macro.escape(ignored_terms))
@@ -84,6 +85,7 @@ defmodule RDF.Vocabulary.Namespace do
 
         define_vocab_terms unquote(lowercased_terms), unquote(base_iri)
 
+        @impl Elixir.RDF.Namespace
         def __resolve_term__(term) do
           case @terms[term] do
             nil ->