diff --git a/src/viewport.cpp b/src/viewport.cpp
index f38cf813da..01d6c70897 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -205,12 +205,6 @@ static Point MapXYZToViewport(const Viewport &vp, int x, int y, int z)
 	return p;
 }
 
-void DeleteWindowViewport(Window *w)
-{
-	delete w->viewport;
-	w->viewport = nullptr;
-}
-
 /**
  * Initialize viewport of the window for use.
  * @param w Window to use/display the viewport in
@@ -226,7 +220,7 @@ void InitializeWindowViewport(Window *w, int x, int y,
 {
 	assert(w->viewport == nullptr);
 
-	ViewportData *vp = new ViewportData();
+	auto vp = std::make_unique<ViewportData>();
 
 	vp->left = x + w->left;
 	vp->top = y + w->top;
@@ -272,9 +266,10 @@ void InitializeWindowViewport(Window *w, int x, int y,
 
 	vp->overlay = nullptr;
 
-	w->viewport = vp;
 	vp->virtual_left = 0;
 	vp->virtual_top = 0;
+
+	w->viewport = std::move(vp);
 }
 
 static Point _vp_move_offs;
@@ -415,7 +410,7 @@ Viewport *IsPtInWindowViewport(const Window *w, int x, int y)
 	if (w->viewport == nullptr) return nullptr;
 
 	const Viewport &vp = *w->viewport;
-	if (IsInsideMM(x, vp.left, vp.left + vp.width) && IsInsideMM(y, vp.top, vp.top + vp.height)) return w->viewport;
+	if (IsInsideMM(x, vp.left, vp.left + vp.width) && IsInsideMM(y, vp.top, vp.top + vp.height)) return w->viewport.get();
 
 	return nullptr;
 }
diff --git a/src/viewport_func.h b/src/viewport_func.h
index 0a45dab931..88e00edd73 100644
--- a/src/viewport_func.h
+++ b/src/viewport_func.h
@@ -21,7 +21,6 @@ static const int TILE_HEIGHT_STEP = 50; ///< One Z unit tile height difference i
 
 void SetSelectionRed(bool);
 
-void DeleteWindowViewport(Window *w);
 void InitializeWindowViewport(Window *w, int x, int y, int width, int height, std::variant<TileIndex, VehicleID> focus, ZoomLevel zoom);
 Viewport *IsPtInWindowViewport(const Window *w, int x, int y);
 Point TranslateXYToTileCoord(const Viewport &vp, int x, int y, bool clamp_to_map = true);
diff --git a/src/window.cpp b/src/window.cpp
index 415abbe5f1..0e36096d2a 100644
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -1090,8 +1090,6 @@ Window::~Window()
 {
 	/* Make sure the window is closed, deletion is allowed only in Window::DeleteClosedWindows(). */
 	assert(*this->z_position == nullptr);
-
-	if (this->viewport != nullptr) DeleteWindowViewport(this);
 }
 
 /**
diff --git a/src/window_gui.h b/src/window_gui.h
index 9b27432192..6da0e607a9 100644
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -316,7 +316,7 @@ public:
 
 	Owner owner = INVALID_OWNER; ///< The owner of the content shown in this window. Company colour is acquired from this variable.
 
-	ViewportData *viewport = nullptr; ///< Pointer to viewport data, if present.
+	std::unique_ptr<ViewportData> viewport; ///< Pointer to viewport data, if present.
 	const NWidgetCore *nested_focus = nullptr; ///< Currently focused nested widget, or \c nullptr if no nested widget has focus.
 	std::map<WidgetID, QueryString*> querystrings{}; ///< QueryString associated to WWT_EDITBOX widgets.
 	std::unique_ptr<NWidgetBase> nested_root{}; ///< Root of the nested tree.