diff --git a/src/ui/bigtext/bigtext.py b/src/ui/bigtext/bigtext.py
index 3854eba..3985eac 100644
--- a/src/ui/bigtext/bigtext.py
+++ b/src/ui/bigtext/bigtext.py
@@ -452,9 +452,11 @@ class InnerBigText(QWidget):
 
     def _select_all(self):
         self.selection_highlight.start_byte = self.model.get_line_start_at(self._range_start)
-        end_byte = self.model.byte_count() if self._range_end < 0 else min(
-            self.model.byte_count(), self._range_end)
-        self.selection_highlight.end_byte = self.model.get_line_end_at(end_byte)
+        if self._range_end < 0 or self.model.byte_count() <= self._range_end:
+            self.selection_highlight.end_byte = self.model.byte_count()
+        else:
+            self.selection_highlight.end_byte = self.model.get_line_start_at(self._range_end)
+
         self._update_highlight_selected_text()
         self.update()