diff --git a/reader/HDF5MetadataSource.cpp b/reader/HDF5MetadataSource.cpp
index 989f9102..27eb96d3 100644
--- a/reader/HDF5MetadataSource.cpp
+++ b/reader/HDF5MetadataSource.cpp
@@ -141,6 +141,7 @@ bool ReadReflectionsFromGroup(HDF5Object &file,
     auto h = file.ReadOptVector<int32_t>(image_group_name + "/h");
     auto k = file.ReadOptVector<int32_t>(image_group_name + "/k");
     auto l = file.ReadOptVector<int32_t>(image_group_name + "/l");
+    auto image_number = file.ReadOptVector<float>(image_group_name + "/observed_frame");
     auto predicted_x = file.ReadOptVector<float>(image_group_name + "/predicted_x");
     auto predicted_y = file.ReadOptVector<float>(image_group_name + "/predicted_y");
     auto obs_x = file.ReadOptVector<float>(image_group_name + "/observed_x");
@@ -157,7 +158,8 @@ bool ReadReflectionsFromGroup(HDF5Object &file,
 
     if (h.size() != l.size() || h.size() != k.size() || h.size() != d.size()
         || h.size() != predicted_x.size() || h.size() != predicted_y.size()
-        || h.size() != int_sum.size() || h.size() != int_err.size() || h.size() != bkg.size())
+        || h.size() != int_sum.size() || h.size() != int_err.size() || h.size() != bkg.size()
+        || h.size() != image_number.size())
         throw JFJochException(JFJochExceptionCategory::HDF5, "Wrong size of reflections dataset");
 
     for (size_t i = 0; i < h.size(); i++) {
@@ -191,6 +193,7 @@ bool ReadReflectionsFromGroup(HDF5Object &file,
             .h = h.at(i),
             .k = k.at(i),
             .l = l.at(i),
+            .image_number = image_number.at(i),
             .delta_phi_deg = delta_phi_val,
             .predicted_x = predicted_x.at(i),
             .predicted_y = predicted_y.at(i),