diff --git a/fsl/fsleyes/gl/lightboxcanvas.py b/fsl/fsleyes/gl/lightboxcanvas.py
index 7be390ecc3936c9ae8cabc3d4fbdc0bdfca72e38..6f2b78e1ab9bab58bf5f8721def330221c3b4941 100644
--- a/fsl/fsleyes/gl/lightboxcanvas.py
+++ b/fsl/fsleyes/gl/lightboxcanvas.py
@@ -371,7 +371,7 @@ class LightBoxCanvas(slicecanvas.SliceCanvas):
 
                 globj = self._glObjects.get(overlay, None)
 
-                if globj is None:
+                if (globj is None) or (not globj):
                     continue
                 
                 rt, name = self._getPreRenderTexture(globj, overlay)
diff --git a/fsl/fsleyes/gl/slicecanvas.py b/fsl/fsleyes/gl/slicecanvas.py
index 12cc0801e0c318e6ba4fe55b0c308c6d4afac7e8..589add25114187f26f8e37b1d7def20cac5fdf2c 100644
--- a/fsl/fsleyes/gl/slicecanvas.py
+++ b/fsl/fsleyes/gl/slicecanvas.py
@@ -463,7 +463,7 @@ class SliceCanvas(props.HasProperties):
             globj   = self._glObjects.get(overlay, None)
             display = self.displayCtx.getDisplay(overlay)
 
-            if globj is None:
+            if (globj is None) or (not globj):
                 continue
 
             # For offscreen render mode, GLObjects are
@@ -687,7 +687,7 @@ class SliceCanvas(props.HasProperties):
 
         for ovl, globj in self._glObjects.items():
 
-            if globj is not None:
+            if (globj is not None) and globj:
                 globj.setAxes(self.xax, self.yax)
 
         self._overlayBoundsChanged()