diff --git a/notebooks/DrizzlePac/optimize_image_sampling/optimize_image_sampling.ipynb b/notebooks/DrizzlePac/optimize_image_sampling/optimize_image_sampling.ipynb
index 2a18e775..e5a4c0de 100644
--- a/notebooks/DrizzlePac/optimize_image_sampling/optimize_image_sampling.ipynb
+++ b/notebooks/DrizzlePac/optimize_image_sampling/optimize_image_sampling.ipynb
@@ -402,7 +402,7 @@
    "source": [
     "mdz = fits.getval(flt_files[0], 'MDRIZTAB', ext=0).split('$')[1]\n",
     "print('Searching for the MDRIZTAB file:', mdz)\n",
-    "get_mdriztab = os.system('crds sync --hst --files '+mdz+' --output-dir '+os.environ['iref'])"
+    "!crds sync --hst --files {mdz} --output-dir {os.environ['iref']}"
    ]
   },
   {