diff --git a/PorygonSharp/CoreSetup.cs b/PorygonSharp/CoreSetup.cs
index db15171..f764f4d 100644
--- a/PorygonSharp/CoreSetup.cs
+++ b/PorygonSharp/CoreSetup.cs
@@ -8,14 +8,14 @@ namespace PorygonSharp
         public static Action<string> Print = Console.WriteLine;
 
         private delegate void InternalPrintDelegate(IntPtr ptr);
-        private static InternalPrintDelegate InternalPrint = PrintFunc;
+        private static readonly InternalPrintDelegate InternalPrint = PrintFunc;
 
         static CoreSetup()
         {
             SetPrintFunc();
         }
-        
-        internal static void SetPrintFunc()
+
+        private static void SetPrintFunc()
         {
             var funcPtr = Marshal.GetFunctionPointerForDelegate(InternalPrint);
             InternalSetPrintFunc(funcPtr);
diff --git a/PorygonSharp/EvaluateResult.cs b/PorygonSharp/EvaluateResult.cs
new file mode 100644
index 0000000..d63afe2
--- /dev/null
+++ b/PorygonSharp/EvaluateResult.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace PorygonSharp
+{
+    internal struct EvaluateResult : IDisposable
+    {
+        [StructLayout(LayoutKind.Sequential)]
+        private struct EvaluateResultInternal
+        {
+            public readonly IntPtr Value;
+            public readonly byte Result;
+        }
+
+        private readonly IntPtr _ptr;
+        private readonly EvaluateResultInternal _internal;
+        public EvaluateResult(IntPtr ptr)
+        {
+            _ptr = ptr;
+            _internal = Marshal.PtrToStructure<EvaluateResultInternal>(ptr);
+        }
+
+        public EvalValue GetValue()
+        {
+            return !IsSuccess() ? null : new EvalValue(_internal.Value);
+        }
+
+        public bool IsSuccess()
+        {
+            return _internal.Result == 0;
+        }
+
+        public string GetError()
+        {
+            return GetErrorMessage(_ptr);
+        }
+
+        public void Dispose()
+        {
+            Marshal.FreeHGlobal(_ptr);
+        }
+        
+        [DllImport("libPorygonLang", EntryPoint = "GetResultError", CallingConvention = CallingConvention.Cdecl)]
+        private static extern string GetErrorMessage(IntPtr ptr);
+
+    }
+}
\ No newline at end of file
diff --git a/PorygonSharp/EvaluationException.cs b/PorygonSharp/EvaluationException.cs
new file mode 100644
index 0000000..a9baaf1
--- /dev/null
+++ b/PorygonSharp/EvaluationException.cs
@@ -0,0 +1,12 @@
+using System;
+
+namespace PorygonSharp
+{
+    public class EvaluationException : Exception
+    {
+        public EvaluationException(string message) : base(message)
+        {
+            
+        }
+    }
+}
\ No newline at end of file
diff --git a/PorygonSharp/Script.cs b/PorygonSharp/Script.cs
index ed2f395..54f843b 100644
--- a/PorygonSharp/Script.cs
+++ b/PorygonSharp/Script.cs
@@ -1,7 +1,9 @@
 using System;
 using System.Linq;
 using System.Runtime.CompilerServices;
+using System.Runtime.ExceptionServices;
 using System.Runtime.InteropServices;
+using System.Security;
 using PorygonSharp.DiagnosticHandling;
 
 namespace PorygonSharp
@@ -56,18 +58,20 @@ namespace PorygonSharp
         {
             Marshal.FreeHGlobal(_internalScriptHandle);
         }
-
-        public void Evaluate()
+        
+        public EvalValue Evaluate()
         {
-            Evaluate(_internalScriptHandle);
+            var ptr = Evaluate(_internalScriptHandle);
+            using (var result = new EvaluateResult(ptr))
+            {
+                if (result.IsSuccess())
+                {
+                    return result.GetValue();
+                }
+                throw new EvaluationException(result.GetError());
+            }
         }
-
-        public EvalValue GetLastValue()
-        {
-            var ptr = GetLastValue(_internalScriptHandle);
-            return new EvalValue(ptr);
-        }
-
+        
         public bool HasVariable(string key)
         {
             return HasVariable(_internalScriptHandle, key);
@@ -94,9 +98,7 @@ namespace PorygonSharp
         [DllImport("libPorygonLang", EntryPoint = "CreateScript", CallingConvention = CallingConvention.Cdecl)]
         private static extern IntPtr Create([MarshalAs(UnmanagedType.LPWStr)]string s);
         [DllImport("libPorygonLang", EntryPoint = "EvaluateScript", CallingConvention = CallingConvention.Cdecl)]
-        private static extern void Evaluate(IntPtr script);
-        [DllImport("libPorygonLang", EntryPoint = "GetLastValue", CallingConvention = CallingConvention.Cdecl)]
-        private static extern IntPtr GetLastValue(IntPtr script);
+        private static extern IntPtr Evaluate(IntPtr script);
         [DllImport("libPorygonLang", EntryPoint = "HasVariable", CallingConvention = CallingConvention.Cdecl)]
         private static extern bool HasVariable(IntPtr script, [MarshalAs(UnmanagedType.LPWStr)]string key);
         [DllImport("libPorygonLang", EntryPoint = "GetVariable", CallingConvention = CallingConvention.Cdecl)]
diff --git a/PorygonSharpTests/UnitTest1.cs b/PorygonSharpTests/UnitTest1.cs
index eaf080e..418ef74 100644
--- a/PorygonSharpTests/UnitTest1.cs
+++ b/PorygonSharpTests/UnitTest1.cs
@@ -36,10 +36,9 @@ namespace PorygonSharpTests
         {
             using (var script = new Script("1+10"))
             {
-                script.Evaluate();
-                var lastVal = script.GetLastValue();
-                Assert.AreEqual(TypeClass.Number, lastVal.GetTypeClass());
-                var val = lastVal.EvaluateInteger();
+                var result = script.Evaluate();
+                Assert.AreEqual(TypeClass.Number, result.GetTypeClass());
+                var val = result.EvaluateInteger();
                 Assert.AreEqual(11, val);
             }
         }
@@ -49,10 +48,9 @@ namespace PorygonSharpTests
         {
             using (var script = new Script("1+10.24"))
             {
-                script.Evaluate();
-                var lastVal = script.GetLastValue();
-                Assert.AreEqual(TypeClass.Number, lastVal.GetTypeClass());
-                var val = lastVal.EvaluateFloat();
+                var result = script.Evaluate();
+                Assert.AreEqual(TypeClass.Number, result.GetTypeClass());
+                var val = result.EvaluateFloat();
                 Assert.AreEqual(11.24d, val, 5);
             }
         }
@@ -62,10 +60,9 @@ namespace PorygonSharpTests
         {
             using (var script = new Script("true and true"))
             {
-                script.Evaluate();
-                var lastVal = script.GetLastValue();
-                Assert.AreEqual(TypeClass.Bool, lastVal.GetTypeClass());
-                var val = lastVal.EvaluateBool();
+                var result = script.Evaluate();
+                Assert.AreEqual(TypeClass.Bool, result.GetTypeClass());
+                var val = result.EvaluateBool();
                 Assert.AreEqual(true, val);
             }
         }
@@ -75,10 +72,9 @@ namespace PorygonSharpTests
         {
             using (var script = new Script("'foo' + 'bar'"))
             {
-                script.Evaluate();
-                var lastVal = script.GetLastValue();
-                Assert.AreEqual(TypeClass.String, lastVal.GetTypeClass());
-                var val = lastVal.EvaluateString();
+                var result = script.Evaluate();
+                Assert.AreEqual(TypeClass.String, result.GetTypeClass());
+                var val = result.EvaluateString();
                 Assert.AreEqual("foobar", val);
             }
         }
@@ -102,7 +98,9 @@ namespace PorygonSharpTests
             using (var script = new Script("function add(number a, number b) result = a + b end"))
             {
                 script.Evaluate();
+                Assert.That(script.HasFunction("add"));
                 script.CallFunction("add", 100, 50);
+                
                 var variable = script.GetVariable("result");
                 Assert.AreEqual(TypeClass.Number, variable.GetTypeClass());
                 var val = variable.EvaluateInteger();
@@ -139,6 +137,16 @@ namespace PorygonSharpTests
             }
         }
 
+        [Test]
+        public void TestExceptions()
+        {
+            using (var script = new Script("error('test')"))
+            {
+                Assert.Throws<EvaluationException>(() => script.Evaluate());
+            }
+        }
+        
+
         [Test]
         public void TestHash()
         {
diff --git a/libPorygonLang.so b/libPorygonLang.so
index b155a2b..5b3bc89 100755
Binary files a/libPorygonLang.so and b/libPorygonLang.so differ