diff --git a/notebooks/AGIPD/Characterize_AGIPD_Gain_Darks_NBC.ipynb b/notebooks/AGIPD/Characterize_AGIPD_Gain_Darks_NBC.ipynb
index 003bab0b3856619b104c5b207ed7a4878adade80..ba2a74c76b9b1db27cc42e5873b42424d5054450 100644
--- a/notebooks/AGIPD/Characterize_AGIPD_Gain_Darks_NBC.ipynb
+++ b/notebooks/AGIPD/Characterize_AGIPD_Gain_Darks_NBC.ipynb
@@ -40,6 +40,7 @@
     "cal_db_timeout = 3000000 # timeout on caldb requests\"\n",
     "local_output = True # output constants locally\n",
     "db_output = False # output constants to database\n",
+    "sort_runs = True  # Sort the selected dark runs. This flag is added for old data (e.g. 900174 r0011).\n",
     "\n",
     "mem_cells = 0 # number of memory cells used, set to 0 to automatically infer\n",
     "bias_voltage = 0 # bias voltage, set to 0 to use stored value in slow data.\n",
@@ -268,7 +269,8 @@
     "    image_src=instrument_src_mod,\n",
     "    ctrl_src=ctrl_src,\n",
     ")\n",
-    "agipd_ctrl_dark.sort_dark_runs()\n",
+    "if sort_runs:\n",
+    "    agipd_ctrl_dark.sort_dark_runs()\n",
     "\n",
     "if mem_cells == 0:\n",
     "    mem_cells = agipd_ctrl_dark.get_memory_cells()\n",