diff --git a/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Mode.xsd b/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Mode.xsd
index 1297c6e1b3..81a79dc62f 100644
--- a/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Mode.xsd
+++ b/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Mode.xsd
@@ -188,8 +188,9 @@
 	<!-- A grouping of keywords that sholuld be colored the same way -->
 	<xsd:complexType name="KeyWords">
 		<xsd:sequence>
+			<!-- allow groups with 0 keywords: this simplifies the syntax highlighting editor -->
 			<!-- A KeyWord -->
-			<xsd:element name="Key" type="Key" minOccurs="1" maxOccurs="unbounded">
+			<xsd:element name="Key" type="Key" minOccurs="0" maxOccurs="unbounded">
 			</xsd:element>
 		</xsd:sequence>
 		<!-- The name of the KeyWord group -->
diff --git a/src/Libraries/ICSharpCode.TextEditor/Project/Src/Gui/TextEditorControlBase.cs b/src/Libraries/ICSharpCode.TextEditor/Project/Src/Gui/TextEditorControlBase.cs
index 4229b37ba6..1e05721d95 100644
--- a/src/Libraries/ICSharpCode.TextEditor/Project/Src/Gui/TextEditorControlBase.cs
+++ b/src/Libraries/ICSharpCode.TextEditor/Project/Src/Gui/TextEditorControlBase.cs
@@ -624,7 +624,11 @@ namespace ICSharpCode.TextEditor
 			document.UndoStack.ClearAll();
 			document.BookmarkManager.Clear();
 			if (autoLoadHighlighting) {
-				document.HighlightingStrategy = HighlightingStrategyFactory.CreateHighlightingStrategyForFile(fileName);
+				try {
+					document.HighlightingStrategy = HighlightingStrategyFactory.CreateHighlightingStrategyForFile(fileName);
+				} catch (HighlightingDefinitionInvalidException ex) {
+					MessageBox.Show(ex.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+				}
 			}
 			
 			if (autodetectEncoding) {