diff --git a/tools/jfjoch_process.cpp b/tools/jfjoch_process.cpp
index 20e67be5..396c1cb2 100644
--- a/tools/jfjoch_process.cpp
+++ b/tools/jfjoch_process.cpp
@@ -141,7 +141,7 @@ int main(int argc, char **argv) {
     bool refine_beam_center = true;
     bool run_scaling = false;
     bool anomalous_mode = false;
-    std::optional<int> space_group_number;
+    std::optional<int64_t> space_group_number;
     std::optional<UnitCell> fixed_reference_unit_cell;
     std::optional<int64_t> max_spot_count_override;
     float sigma_spot_finding = 3.0;
@@ -328,6 +328,7 @@ int main(int argc, char **argv) {
     experiment.OverwriteExistingFiles(true);
     experiment.PolarizationFactor(0.99);
     experiment.SetFileWriterFormat(FileWriterFormat::NXmxLegacy);
+    experiment.SpaceGroupNumber(space_group_number);
 
     if (fixed_reference_unit_cell.has_value())
         experiment.SetUnitCell(*fixed_reference_unit_cell);