diff --git a/image_analysis/lattice_search/LatticeSearch.cpp b/image_analysis/lattice_search/LatticeSearch.cpp
index b60c3c388..de3e127c3 100644
--- a/image_analysis/lattice_search/LatticeSearch.cpp
+++ b/image_analysis/lattice_search/LatticeSearch.cpp
@@ -480,10 +480,19 @@ std::optional<LatticeSearchResult> SearchCharacters(const CrystalLattice &L, dou
     // class than the table, take it - held to this call's own tolerances, so a search that grants no
     // length equality still grants none.
     //
+    // Only for a class that equates lengths (tetragonal, trigonal, hexagonal, cubic): those are the
+    // lattices whose degenerate shortest vectors give the table more than one reduced cell. A class
+    // carried by its angles alone the table reads on any of them, and where it refuses one the
+    // two-folds would grant, the angle is not there: measured on monoclinic crystals with
+    // pseudo-orthorhombic metrics (and a triclinic one with a pseudo-I-orthorhombic one), Le Page
+    // promoted at 0.2-1 deg obliquity, the constrained cell was integrated and every one merged
+    // worse (ISa 46 -> 17 on one, CC1/2 0.98 -> 0.45 on another).
+    //
     // A tetragonal or cubic cell refused only on its length equality is, on its angles alone, the
     // orthorhombic lattice of the same centring in the same basis - the class a search granting no
     // length equality has to return, as the table did for the settings it could read.
-    if (auto lp = LePageLattice(L, std::min(angle_tolerance, LATTICE_MAX_OBLIQUITY_DEG))) {
+    if (auto lp = LePageLattice(L, std::min(angle_tolerance, LATTICE_MAX_OBLIQUITY_DEG));
+        lp && ClassImposesLengthEquality(lp->system)) {
         const auto [angle, length] = ClassMetricDeparture(lp->conventional.GetUnitCell(), lp->system);
         if (length > dist_tolerance && (lp->system == gemmi::CrystalSystem::Tetragonal
                                         || lp->system == gemmi::CrystalSystem::Cubic))