diff --git a/OSCADSharp/OSCADSharp.UnitTests/OSCADObjectTests.cs b/OSCADSharp/OSCADSharp.UnitTests/OSCADObjectTests.cs
index de5cb5f..dc040e0 100644
--- a/OSCADSharp/OSCADSharp.UnitTests/OSCADObjectTests.cs
+++ b/OSCADSharp/OSCADSharp.UnitTests/OSCADObjectTests.cs
@@ -158,8 +158,8 @@ namespace OSCADSharp.UnitTests
         public void OSCADObject_ToFileIncludesGlobalVariablesDefinedInSettings()
         {
             var cube = new Cube();
-            string[] output = null;
             Settings.Globals["$fn"] = 100;
+            string[] output = null;
 
             var mock = new Mock<IFileWriter>();
             mock.Setup(_wrtr => _wrtr.WriteAllLines(It.IsAny<string>(), It.IsAny<string[]>()))
@@ -167,8 +167,8 @@ namespace OSCADSharp.UnitTests
             Settings.FileWriter = mock.Object;
 
             cube.ToFile("myFile");
-
-            Assert.AreEqual("$fn = 100;\r\n", output[1]);
+            bool outputMatches = "$fn = 100;\r\n" == output[1];
+            Assert.IsTrue(outputMatches);
         }
     }
 }
diff --git a/OSCADSharp/OSCADSharp.UnitTests/OSCADSharp.UnitTests.csproj b/OSCADSharp/OSCADSharp.UnitTests/OSCADSharp.UnitTests.csproj
index 83c374d..6cd12b4 100644
--- a/OSCADSharp/OSCADSharp.UnitTests/OSCADSharp.UnitTests.csproj
+++ b/OSCADSharp/OSCADSharp.UnitTests/OSCADSharp.UnitTests.csproj
@@ -56,6 +56,7 @@
     </Otherwise>
   </Choose>
   <ItemGroup>
+    <Compile Include="SettingsTests.cs" />
     <Compile Include="Solids\CubeTests.cs" />
     <Compile Include="Solids\CylinderTests.cs" />
     <Compile Include="Transforms\HullTests.cs" />
diff --git a/OSCADSharp/OSCADSharp.UnitTests/SettingsTests.cs b/OSCADSharp/OSCADSharp.UnitTests/SettingsTests.cs
new file mode 100644
index 0000000..fc7f345
--- /dev/null
+++ b/OSCADSharp/OSCADSharp.UnitTests/SettingsTests.cs
@@ -0,0 +1,33 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+using OSCADSharp.Scripting;
+using OSCADSharp.Solids;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace OSCADSharp.UnitTests
+{
+    [TestClass]
+    public class SettingsTests
+    {
+        [TestMethod]
+        public void Settings_NullVariablesDoNothing()
+        {
+            var cube = new Cube();
+            Settings.Globals["thing"] = null;
+            string[] output = null;
+
+            var mock = new Mock<IFileWriter>();
+            mock.Setup(_wrtr => _wrtr.WriteAllLines(It.IsAny<string>(), It.IsAny<string[]>()))
+                .Callback<string, string[]>((path, contents) => { output = contents; });
+            Settings.FileWriter = mock.Object;
+
+            cube.ToFile("myFile");
+
+            Assert.AreEqual("", output[1]);
+        }
+    }
+}
diff --git a/OSCADSharp/OSCADSharp/Scripting/Variables.cs b/OSCADSharp/OSCADSharp/Scripting/Variables.cs
index 1a47561..397aad9 100644
--- a/OSCADSharp/OSCADSharp/Scripting/Variables.cs
+++ b/OSCADSharp/OSCADSharp/Scripting/Variables.cs
@@ -54,6 +54,11 @@ namespace OSCADSharp.Scripting
             StringBuilder sb = new StringBuilder();
             foreach (var kvp in this.variables)
             {
+                if(kvp.Value == null || String.IsNullOrEmpty(kvp.Value.ToString()) || String.IsNullOrEmpty(kvp.Key))
+                {
+                    continue;
+                }
+
                 sb.Append(kvp.Key);
                 sb.Append(" = ");
                 sb.Append(kvp.Value);