diff --git a/src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/Options/NamedColorHighlightingItem.cs b/src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/Options/NamedColorHighlightingItem.cs
index 5bc0f4cd7f..e5176fdc80 100644
--- a/src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/Options/NamedColorHighlightingItem.cs
+++ b/src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/Options/NamedColorHighlightingItem.cs
@@ -70,7 +70,7 @@ namespace ICSharpCode.AvalonEdit.AddIn.Options
 		
 		public bool Underline {
 			get {
-				return color.Underline;
+				return color.Underline == true;
 			}
 			set {
 				throw new NotSupportedException();
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/HighlightingColor.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/HighlightingColor.cs
index 163444c111..6dfb652d05 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/HighlightingColor.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/HighlightingColor.cs
@@ -86,8 +86,8 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 		}
 		
 		/// <summary>
-      ///  Gets/sets the underline flag. Null if the underline status does not change the font style.
-      /// </summary>
+		///  Gets/sets the underline flag. Null if the underline status does not change the font style.
+		/// </summary>
 		public bool? Underline {
 			get {
 				return underline;
@@ -97,7 +97,7 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 					throw new InvalidOperationException();
 				underline = value;
 			}
-      }    
+		}
 		
 		/// <summary>
 		/// Gets/sets the foreground color applied by the highlighting.
@@ -146,6 +146,8 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 				this.FontWeight = System.Windows.FontWeight.FromOpenTypeWeight(info.GetInt32("Weight"));
 			if (info.GetBoolean("HasStyle"))
 				this.FontStyle = (FontStyle?)new FontStyleConverter().ConvertFromInvariantString(info.GetString("Style"));
+			if (info.GetBoolean("HasUnderline"))
+				this.Underline = info.GetBoolean("Underline");
 			this.Foreground = (HighlightingBrush)info.GetValue("Foreground", typeof(HighlightingBrush));
 			this.Background = (HighlightingBrush)info.GetValue("Background", typeof(HighlightingBrush));
 		}
@@ -169,6 +171,9 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 			info.AddValue("HasStyle", this.FontStyle.HasValue);
 			if (this.FontStyle.HasValue)
 				info.AddValue("Style", this.FontStyle.Value.ToString());
+			info.AddValue("HasUnderline", this.Underline.HasValue);
+			if (this.Underline.HasValue)
+				info.AddValue("Underline", this.Underline.Value);
 			info.AddValue("Foreground", this.Foreground);
 			info.AddValue("Background", this.Background);
 		}
@@ -196,6 +201,12 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 				b.Append(FontStyle.Value.ToString().ToLowerInvariant());
 				b.Append("; ");
 			}
+			if (Underline != null)
+			{
+				b.Append("text-decoration: ");
+				b.Append(Underline.Value ? "underline" : "none");
+				b.Append("; ");
+			}
 			return b.ToString();
 		}
 		
@@ -247,7 +258,9 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 		{
 			if (other == null)
 				return false;
-			return this.name == other.name && this.fontWeight == other.fontWeight && this.fontStyle == other.fontStyle && object.Equals(this.foreground, other.foreground) && object.Equals(this.background, other.background);
+			return this.name == other.name && this.fontWeight == other.fontWeight
+				&& this.fontStyle == other.fontStyle && this.underline == other.underline
+				&& object.Equals(this.foreground, other.foreground) && object.Equals(this.background, other.background);
 		}
 		
 		/// <inheritdoc/>
@@ -282,11 +295,14 @@ namespace ICSharpCode.AvalonEdit.Highlighting
 				this.foreground = color.foreground;
 			if (color.background != null)
 				this.background = color.background;
+			if (color.underline != null)
+				this.underline = color.underline;
 		}
 		
 		internal bool IsEmptyForMerge {
 			get {
-				return fontWeight == null && fontStyle == null && foreground == null && background == null;
+				return fontWeight == null && fontStyle == null && underline == null
+					&& foreground == null && background == null;
 			}
 		}
 	}
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Resources/ModeV2.xsd b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Resources/ModeV2.xsd
index 1a9c463960..c2e242ac28 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Resources/ModeV2.xsd
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Resources/ModeV2.xsd
@@ -24,7 +24,6 @@
 	<xsd:simpleType name="FontStyle">
 		<xsd:restriction base="xsd:string">
 			<xsd:enumeration value="italic"/>
-		   <xsd:enumeration value="underlined"/>
 			<xsd:enumeration value="normal"/>
 			<xsd:enumeration value="oblique"/>
 		</xsd:restriction>
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/V2Loader.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/V2Loader.cs
index 70b2539dc8..b9b81d1dec 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/V2Loader.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/V2Loader.cs
@@ -297,7 +297,7 @@ namespace ICSharpCode.AvalonEdit.Highlighting.Xshd
 			color.Background = ParseColor(position, reader.GetAttribute("background"));
 			color.FontWeight = ParseFontWeight(reader.GetAttribute("fontWeight"));
 			color.FontStyle = ParseFontStyle(reader.GetAttribute("fontStyle"));
-			color.Underline = reader.GetAttribute("underline") == "true";
+			color.Underline = reader.GetBoolAttribute("underline");
 			return color;
 		}
 		
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/XshdColor.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/XshdColor.cs
index 5213eeee34..a6968508b8 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/XshdColor.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Highlighting/Xshd/XshdColor.cs
@@ -52,7 +52,7 @@ namespace ICSharpCode.AvalonEdit.Highlighting.Xshd
 		/// <summary>
 		/// Gets/sets the underline flag
 		/// </summary>
-		public bool Underline { get; set; }
+		public bool? Underline { get; set; }
 		
 		/// <summary>
 		/// Gets/sets the font style.
@@ -86,7 +86,8 @@ namespace ICSharpCode.AvalonEdit.Highlighting.Xshd
 			if (info.GetBoolean("HasStyle"))
 				this.FontStyle = (FontStyle?)new FontStyleConverter().ConvertFromInvariantString(info.GetString("Style"));
 			this.ExampleText = info.GetString("ExampleText");
-			this.Underline = info.GetBoolean("Underline");
+			if (info.GetBoolean("HasUnderline"))
+				this.Underline = info.GetBoolean("Underline");
 		}
 		
 		/// <summary>
@@ -104,9 +105,10 @@ namespace ICSharpCode.AvalonEdit.Highlighting.Xshd
 			info.AddValue("Name", this.Name);
 			info.AddValue("Foreground", this.Foreground);
 			info.AddValue("Background", this.Background);
+			info.AddValue("HasUnderline", this.Underline.HasValue);
+			if (this.Underline.HasValue)
+				info.AddValue("Underline", this.Underline.Value);
 			info.AddValue("HasWeight", this.FontWeight.HasValue);
-			if (this.Underline)
-				info.AddValue("Underline", this.Underline);			
 			if (this.FontWeight.HasValue)
 				info.AddValue("Weight", this.FontWeight.Value.ToOpenTypeWeight());
 			info.AddValue("HasStyle", this.FontStyle.HasValue);