diff --git a/CHANGELOG.md b/CHANGELOG.md
index 50a524f..9fc8e10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 
 ### Fixed
 
+- numeric operations on invalid numeric literals no longer fail, but return `nil` instead    
 - BEAM error warnings when trying to use top-level modules as vocabulary terms 
 
 
diff --git a/lib/rdf/xsd/datatypes/numeric.ex b/lib/rdf/xsd/datatypes/numeric.ex
index c1b27aa..dbfd2fe 100644
--- a/lib/rdf/xsd/datatypes/numeric.ex
+++ b/lib/rdf/xsd/datatypes/numeric.ex
@@ -517,7 +517,8 @@ defmodule RDF.XSD.Numeric do
   defp arithmetic_operation(op, %Literal{literal: literal1}, literal2, fun), do: arithmetic_operation(op, literal1, literal2, fun)
   defp arithmetic_operation(op, literal1, %Literal{literal: literal2}, fun), do: arithmetic_operation(op, literal1, literal2, fun)
   defp arithmetic_operation(op, %datatype1{} = literal1, %datatype2{} = literal2, fun) do
-    if datatype?(datatype1) and datatype?(datatype2) do
+    if datatype?(datatype1) and datatype?(datatype2) and
+       Literal.Datatype.valid?(literal1) and Literal.Datatype.valid?(literal2) do
       result_type = result_type(op, datatype1, datatype2)
       {arg1, arg2} = type_conversion(literal1, literal2, result_type)
       result = fun.(arg1.value, arg2.value, result_type)
diff --git a/test/unit/xsd/datatypes/numeric_test.exs b/test/unit/xsd/datatypes/numeric_test.exs
index 2d0918b..98ee426 100644
--- a/test/unit/xsd/datatypes/numeric_test.exs
+++ b/test/unit/xsd/datatypes/numeric_test.exs
@@ -130,7 +130,7 @@ defmodule RDF.XSD.NumericTest do
       assert Numeric.add(@negative_infinity, XSD.double(3.14)) == @negative_infinity
       assert Numeric.add(XSD.double(0), @negative_infinity) == @negative_infinity
       assert Numeric.add(XSD.double(3.14), @negative_infinity) == @negative_infinity
-      assert Numeric.add(@negative_infinity, Age.new(0)) == @negative_infinity
+      assert Numeric.add(@negative_infinity, Age.new(1)) == @negative_infinity
     end
 
     test "if both operands are INF, INF is returned" do
@@ -157,6 +157,14 @@ defmodule RDF.XSD.NumericTest do
       assert Numeric.add(:foo, 42) == nil
       assert Numeric.add(:foo, :bar) == nil
     end
+
+    test "with invalid numeric literals" do
+      refute Numeric.add(XSD.integer("foo"), XSD.integer("bar"))
+      refute Numeric.add(XSD.integer("foo"), XSD.integer(1))
+      refute Numeric.add(XSD.integer(1), XSD.integer("foo"))
+      refute Numeric.add(XSD.integer(1), XSD.byte(300))
+      refute Numeric.add(XSD.integer(1), Age.new(200))
+    end
   end
 
   describe "subtract/2" do