diff --git a/ICSharpCode.Decompiler/IL/ILReader.cs b/ICSharpCode.Decompiler/IL/ILReader.cs
index 19ba9683c..92763b11b 100644
--- a/ICSharpCode.Decompiler/IL/ILReader.cs
+++ b/ICSharpCode.Decompiler/IL/ILReader.cs
@@ -151,7 +151,7 @@ namespace ICSharpCode.Decompiler.IL
 		/// </summary>
 		void Warn(string message)
 		{
-			//Debug.Fail(message);
+			Debug.Fail(message);
 		}
 
 		void ReadInstructions(Dictionary<int, ImmutableArray<StackType>> outputStacks, CancellationToken cancellationToken)
diff --git a/ICSharpCode.Decompiler/IL/Instructions/BinaryNumericInstruction.cs b/ICSharpCode.Decompiler/IL/Instructions/BinaryNumericInstruction.cs
index 457037c1e..0eca8dcf2 100644
--- a/ICSharpCode.Decompiler/IL/Instructions/BinaryNumericInstruction.cs
+++ b/ICSharpCode.Decompiler/IL/Instructions/BinaryNumericInstruction.cs
@@ -59,6 +59,7 @@ namespace ICSharpCode.Decompiler.IL
 			this.Sign = sign;
 			this.CompoundAssignmentType = compoundAssignmentType;
 			this.resultType = ComputeResultType(opCode, left.ResultType, right.ResultType);
+			Debug.Assert(resultType != StackType.Unknown);
 			Debug.Assert(CompoundAssignmentType == CompoundAssignmentType.None || IsValidCompoundAssignmentTarget(Left));
 		}
 		
diff --git a/ICSharpCode.Decompiler/Util/CollectionExtensions.cs b/ICSharpCode.Decompiler/Util/CollectionExtensions.cs
index accb32b73..cd4c7356b 100644
--- a/ICSharpCode.Decompiler/Util/CollectionExtensions.cs
+++ b/ICSharpCode.Decompiler/Util/CollectionExtensions.cs
@@ -19,7 +19,7 @@ namespace ICSharpCode.Decompiler
 		{
 			if (stack.Count == 0)
 				return default(T);
-			return stack.Pop();
+			return stack.Peek();
 		}
 		
 		public static void AddRange<T>(this ICollection<T> collection, IEnumerable<T> input)