diff --git a/mushroom_rl/utils/mujoco/viewer.py b/mushroom_rl/utils/mujoco/viewer.py
index 45cf94fe..8bab2c30 100644
--- a/mushroom_rl/utils/mujoco/viewer.py
+++ b/mushroom_rl/utils/mujoco/viewer.py
@@ -57,9 +57,9 @@ def __init__(self, model, dt, width=1920, height=1080, start_paused=False,
             self._width, self._height = self.update_headless_size(width, height)
         else:
             self._width, self._height = width, height
-            self._window = glfw.create_window(width=self._width, height=self._height, title="MuJoCo", monitor=None, share=None)
             glfw.init()
             glfw.window_hint(glfw.COCOA_RETINA_FRAMEBUFFER, 0)
+            self._window = glfw.create_window(width=self._width, height=self._height, title="MuJoCo", monitor=None, share=None)
             glfw.make_context_current(self._window)
             glfw.set_mouse_button_callback(self._window, self.mouse_button)
             glfw.set_cursor_pos_callback(self._window, self.mouse_move)