diff --git a/QuestPDF/Drawing/TextShaper.cs b/QuestPDF/Drawing/TextShaper.cs
index 85b4f5e..d04612e 100644
--- a/QuestPDF/Drawing/TextShaper.cs
+++ b/QuestPDF/Drawing/TextShaper.cs
@@ -129,6 +129,9 @@ namespace QuestPDF.Drawing
         {
             if (Glyphs.Length == 0)
                 return null;
+
+            if (startIndex > endIndex)
+                return null;
             
             using var skTextBlobBuilder = new SKTextBlobBuilder();
             
diff --git a/QuestPDF/Elements/Text/Items/TextBlockSpan.cs b/QuestPDF/Elements/Text/Items/TextBlockSpan.cs
index ee65d73..033931e 100644
--- a/QuestPDF/Elements/Text/Items/TextBlockSpan.cs
+++ b/QuestPDF/Elements/Text/Items/TextBlockSpan.cs
@@ -66,7 +66,7 @@ namespace QuestPDF.Elements.Text.Items
             // start breaking text from requested position
             var endIndex = TextShapingResult.BreakText(startIndex, request.AvailableWidth);
 
-            if (endIndex < 0)
+            if (endIndex < startIndex)
                 return null;
   
             // break text only on spaces