diff --git a/Source/VirtualTrees.Header.pas b/Source/VirtualTrees.Header.pas
index 76b97e61..a478ffc6 100644
--- a/Source/VirtualTrees.Header.pas
+++ b/Source/VirtualTrees.Header.pas
@@ -5508,7 +5508,7 @@ function TVirtualTreeColumns.GetPreviousColumn(Column : TColumnIndex) : TColumnI
       Result := FPositionToIndex[Position - 1]
     else
       Result := InvalidColumn;
-    Assert(Position <> Result, 'The previous column must not have the same position as the given column.');
+    Assert(Column <> Result, 'The previous column must not have the same position as the given column.');
   end;
 end;