diff --git a/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs b/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
index 5a25661..9963e3c 100644
--- a/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
+++ b/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
@@ -367,10 +367,10 @@
 
         private static object Mod(List<Expression> p)
         {
-            Int32 n = (int)Math.Abs(p[0]);
-            Int32 d = (int)p[1];
-            var ret = n % d;
-            return d < 0 ? ret * -1 : ret;
+            double number = p[0];
+            double divisor = p[1];
+
+            return number - Math.Floor(number / divisor) * divisor;
         }
 
         private static object MRound(List<Expression> p)
diff --git a/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs b/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
index 6d30f1f..2a64f05 100644
--- a/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
+++ b/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
@@ -7,6 +7,8 @@
     [TestFixture]
     public class MathTrigTests
     {
+        private readonly double tolerance = 1e-10;
+
         [Test]
         public void Floor()
         {
@@ -61,5 +63,40 @@
             actual = XLWorkbook.EvaluateExpr(@"FLOOR.MATH(-5.5, 2, -1)");
             Assert.AreEqual(-4, actual);
         }
+
+        [Test]
+        public void Mod()
+        {
+            double actual;
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(1.5, 1)");
+            Assert.AreEqual(0.5, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(3, 2)");
+            Assert.AreEqual(1, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(-3, 2)");
+            Assert.AreEqual(1, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(3, -2)");
+            Assert.AreEqual(-1, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(-3, -2)");
+            Assert.AreEqual(-1, actual, tolerance);
+
+            //////
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(-4.3, -0.5)");
+            Assert.AreEqual(-0.3, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(6.9, -0.2)");
+            Assert.AreEqual(-0.1, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(0.7, 0.6)");
+            Assert.AreEqual(0.1, actual, tolerance);
+
+            actual = (double)XLWorkbook.EvaluateExpr(@"MOD(6.2, 1.1)");
+            Assert.AreEqual(0.7, actual, tolerance);
+        }
     }
 }