diff --git a/ReoGrid/Formula/Evaluator.cs b/ReoGrid/Formula/Evaluator.cs
index bee5e214..f22768fa 100644
--- a/ReoGrid/Formula/Evaluator.cs
+++ b/ReoGrid/Formula/Evaluator.cs
@@ -304,7 +304,15 @@ private static FormulaValue Evaluate(IWorkbook workbook, Cell cell, STNode node)
 						FormulaValue v1 = Evaluate(workbook, cell, node[0]);
 						FormulaValue v2 = Evaluate(workbook, cell, node[1]);
 
-						if (v1.type != v2.type) return true;
+						if (v1.type == FormulaValueType.String && ((string)v1.value) == string.Empty)
+						{
+							if (v2.type == FormulaValueType.Nil) return false;
+						}
+
+						if (v2.type == FormulaValueType.String && ((string)v2.value) == string.Empty)
+						{
+							if (v1.type == FormulaValueType.Nil) return false;
+						}
 
 						switch (v1.type)
 						{
@@ -318,7 +326,7 @@ private static FormulaValue Evaluate(IWorkbook workbook, Cell cell, STNode node)
 								return (bool)v1.value != (bool)v2.value;
 
 							default:
-								return true;
+								return false;
 						}
 					}
 				#endregion // Not Equals
diff --git a/ReoGrid/Formula/Functions.cs b/ReoGrid/Formula/Functions.cs
index 5696e8be..567d8bdc 100644
--- a/ReoGrid/Formula/Functions.cs
+++ b/ReoGrid/Formula/Functions.cs
@@ -883,7 +883,10 @@ public static FormulaValue Or(Cell cell, List<STNode> list)
 				}
 				else if (val.type == FormulaValueType.Number)
 				{
-					return ((double)val.value != 0);
+					if ((double)val.value != 0)
+					{
+						return true;
+					}
 				}
 			}