diff --git a/src/app/ui/timeline/timeline.cpp b/src/app/ui/timeline/timeline.cpp
index 587a02c65..f5de2fc58 100644
--- a/src/app/ui/timeline/timeline.cpp
+++ b/src/app/ui/timeline/timeline.cpp
@@ -1064,7 +1064,7 @@ bool Timeline::onProcessMessage(Message* msg)
         // we shouldn't change the hot (so the separator can be
         // tracked to the mouse's released).
         if (m_clk.part == PART_SEPARATOR) {
-          m_separator_x = std::max(0, mousePos.x);
+          setSeparatorX(mousePos.x);
           layout();
           return true;
         }
@@ -1532,6 +1532,7 @@ void Timeline::onResize(ui::ResizeEvent& ev)
       std::min(sz.w, m_separator_x),
       oneTagHeight()));
 
+  setSeparatorX(m_separator_x);
   updateScrollBars();
 }
 
@@ -4215,4 +4216,9 @@ void Timeline::setLayerCollapsedFlag(const layer_t l, const bool state)
   }
 }
 
+void Timeline::setSeparatorX(int newValue)
+{
+  m_separator_x = base::clamp(newValue, headerBoxWidth(), bounds().w-guiscale());
+}
+
 } // namespace app
diff --git a/src/app/ui/timeline/timeline.h b/src/app/ui/timeline/timeline.h
index f826c9645..823a88533 100644
--- a/src/app/ui/timeline/timeline.h
+++ b/src/app/ui/timeline/timeline.h
@@ -357,6 +357,8 @@ namespace app {
     void setLayerContinuousFlag(const layer_t layer, const bool state);
     void setLayerCollapsedFlag(const layer_t layer, const bool state);
 
+    void setSeparatorX(int newValue);
+
     ui::ScrollBar m_hbar;
     ui::ScrollBar m_vbar;
     gfx::Rect m_viewportArea;