diff --git a/documentation/release_6.3.htm b/documentation/release_6.3.htm
index 90a30cf56..b86be48c2 100644
--- a/documentation/release_6.3.htm
+++ b/documentation/release_6.3.htm
@@ -33,6 +33,10 @@ <h3>New functionality</h3>
   <li>
     <tt>stir_timings</tt> has now an extra option to parse a par-file for a projector-pair.
   </li>
+  <li>
+    Duration in sinogram interfile/exam_info obtained from <tt>lm_to_projdata</tt> has the correct value if we unlist all the events. This is not true for ROOT files<br>
+    <a href=https://github.com/UCL/STIR/pull/1519>PR #1519</a>
+  </li>
 </ul>
 
 
diff --git a/src/listmode_buildblock/LmToProjData.cxx b/src/listmode_buildblock/LmToProjData.cxx
index 9e1a164fc..25dc99b89 100644
--- a/src/listmode_buildblock/LmToProjData.cxx
+++ b/src/listmode_buildblock/LmToProjData.cxx
@@ -448,8 +448,15 @@ LmToProjData::set_up()
   else if (frame_defs.get_num_frames() < 1)
     {
       // make a single frame starting from 0. End value will be ignored.
-      vector<pair<double, double>> frame_times(1, pair<double, double>(0, 0));
-      frame_defs = TimeFrameDefinitions(frame_times);
+      frame_defs = lm_data_ptr->get_exam_info_sptr()->get_time_frame_definitions();
+      if (frame_defs.get_num_time_frames() == 0)
+        {
+          vector<pair<double, double>> frame_times(1, pair<double, double>(0, 0));
+          frame_defs = TimeFrameDefinitions(frame_times);
+        }
+      if (num_events_to_store != 0)
+        warning(
+            "LmToProjData: num_events_to_store has been selected. The frame duration in the Interfile header will be incorrect!");
     }
 
   return Succeeded::yes;