diff --git a/src/dtscalibration/datastore_utils.py b/src/dtscalibration/datastore_utils.py
index 282cf435..f5cb92c7 100644
--- a/src/dtscalibration/datastore_utils.py
+++ b/src/dtscalibration/datastore_utils.py
@@ -260,7 +260,7 @@ def merge_double_ended_times(ds_fw, ds_bw, verify_timedeltas=True, verbose=True)
                     "The following measurements do not belong together, as the time difference\n"
                     "between the\forward and backward measurements is more than 1.5 seconds\n"
                     "larger than the neighboring measurements.\n"
-                    f"FW: {ds_fw.isel(time=itfw).time.values} and BW: {ds_bw.isel(time=itbw).time.values}"
+                    f"FW: {ds_fw.isel(time=itfw).time.values} and BW: {ds_bw.isel(time=itbw).time.values}")
 
     else:
         iuse_chfw2 = iuse_chfw