diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Style/XLFill.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Style/XLFill.cs
index 8e18233..354000d 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Style/XLFill.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Style/XLFill.cs
@@ -51,7 +51,7 @@
                     _container.Styles.ForEach(s => s.Fill.BackgroundColor = value);
                 else
                 {
-                    _patternType = XLFillPatternValues.Solid;
+                    _patternType = value.HasValue ? XLFillPatternValues.Solid : XLFillPatternValues.None;
                     _patternColor = new XLColor(value);
                     _patternBackgroundColor = new XLColor(value);
 
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Styles/XLFillTests.cs b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Styles/XLFillTests.cs
index 913657d..84994d3 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Styles/XLFillTests.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Styles/XLFillTests.cs
@@ -29,5 +29,19 @@
             var fill2 = new XLFill { PatternBackgroundColor = XLColor.Red };
             Assert.IsFalse(fill1.Equals(fill2));
         }
+
+        [TestMethod]
+        public void BackgroundColorSetsPattern()
+        {
+            var fill = new XLFill { BackgroundColor = XLColor.Blue };
+            Assert.AreEqual(XLFillPatternValues.Solid, fill.PatternType);
+        }
+
+        [TestMethod]
+        public void BackgroundNoColorSetsPatternNone()
+        {
+            var fill = new XLFill { BackgroundColor = XLColor.NoColor };
+            Assert.AreEqual(XLFillPatternValues.None, fill.PatternType);
+        }
     }
 }