diff --git a/rugnux/Rugnux.h b/rugnux/Rugnux.h
index 21227a34b..fc61f484d 100644
--- a/rugnux/Rugnux.h
+++ b/rugnux/Rugnux.h
@@ -678,7 +678,8 @@ struct DoubledClassTranslation {
     std::vector<Shell> shells;
 };
 DoubledClassTranslation FitDoubledClassTranslation(const std::vector<MergedReflection> &merged,
-                                                   const UnitCell &doubled_cell, const UnitCell &half_cell);
+                                                   const UnitCell &doubled_cell, const UnitCell &half_cell,
+                                                   char half_centering = 'P');
 
 // Whether two passes hold the same lattice: the same Bravais class and primitive volumes within 2 %.
 bool ArmsHoldSameLattice(const ProcessResult &a, const ProcessResult &b);
diff --git a/rugnux/RugnuxPasses.cpp b/rugnux/RugnuxPasses.cpp
index c2e229fbf..eb0db145d 100644
--- a/rugnux/RugnuxPasses.cpp
+++ b/rugnux/RugnuxPasses.cpp
@@ -1470,14 +1470,15 @@ std::string DoubledCellRises(const ProcessResult::SupercellClass &sc) {
 }
 
 DoubledClassTranslation FitDoubledClassTranslation(const std::vector<MergedReflection> &merged,
-                                                   const UnitCell &doubled_cell, const UnitCell &half_cell) {
+                                                   const UnitCell &doubled_cell, const UnitCell &half_cell,
+                                                   char half_centering) {
     DoubledClassTranslation out;
     // The added class in the written cell: the parity whose sub-lattice is the half cell. Its real lattice
     // is the doubled one plus half of (p0 a + p1 b + p2 c), so one vector the class is odd on is replaced
     // by that half-vector.
     const CrystalLattice dl(doubled_cell);
     const Coord v[3] = {dl.Vec0(), dl.Vec1(), dl.Vec2()};
-    const UnitCell want = CrystalLattice(half_cell).NiggliReduce().GetUnitCell();
+    const UnitCell want = CrystalLattice(half_cell).ToPrimitive(half_centering).NiggliReduce().GetUnitCell();
     double best_mismatch = INFINITY;
     for (int c = 1; c < 8; c++) {
         const std::array<int, 3> p = {(c >> 2) & 1, (c >> 1) & 1, c & 1};
@@ -1681,7 +1682,8 @@ ProcessResult Rugnux::DoubledCellHypothesis(RugnuxObserver *observer, ProcessRes
     // doubled merge, that one translation accounts for most of the class in every shell: the two halves
     // of the cell are then one content displaced, out to the limit (FitDoubledClassTranslation).
     const DoubledClassTranslation tr = FitDoubledClassTranslation(d.merged_reflections, *d.consensus_cell,
-                                                                  *half.consensus_cell);
+                                                                  *half.consensus_cell,
+                                                                  half.consensus_centering.value_or('P'));
     d.merged_reflections.clear();
     const DoubledClassTranslation::Shell *weakest = nullptr;
     std::string table;