diff --git a/notebooks/LPD/LPDChar_Darks_NBC.ipynb b/notebooks/LPD/LPDChar_Darks_NBC.ipynb
index 1c17b282be509aff6c370a8ab6254a5d7294b3dc..68258048916fde65c3f1800c0aba3367173d5b6f 100644
--- a/notebooks/LPD/LPDChar_Darks_NBC.ipynb
+++ b/notebooks/LPD/LPDChar_Darks_NBC.ipynb
@@ -239,7 +239,7 @@
     "    valid = count != 0\n",
     "    count, first = count[valid], first[valid]\n",
     "    first_image = first[skip_first_ntrains]\n",
-    "    last_image = min(first[-1]+count[-1], first_image+ntrains*count[-1])\n",
+    "    last_image = first_image + np.sum(count[skip_first_ntrains:skip_first_ntrains+ntrains])\n",
     "\n",
     "    im = np.array(infile[\"/INSTRUMENT/FXE_DET_LPD1M-1/DET/{}CH0:xtdf/image/data\".format(\n",
     "        channel)][first_image:last_image, ...])\n",