diff --git a/image_analysis/IndexAndRefine.cpp b/image_analysis/IndexAndRefine.cpp
index ac051faf..ac7a9e67 100644
--- a/image_analysis/IndexAndRefine.cpp
+++ b/image_analysis/IndexAndRefine.cpp
@@ -205,6 +205,11 @@ void IndexAndRefine::RefineGeometryIfNeeded(DataMessage &msg, IndexAndRefine::In
         .latt = *outcome.lattice_candidate,
         .crystal_system = outcome.symmetry.crystal_system,
         .min_spots = experiment.GetIndexingSettings().GetViableCellMinSpots(),
+        // Match the [30,150] deg bound the indexers already use (FFBIDXIndexer, FFT settings):
+        // the struct default [60,120] clamps a monoclinic beta outside that window (e.g. NmHR
+        // beta=131.8) to the boundary, corrupting the per-frame cell refinement.
+        .min_angle_deg = 30.0f,
+        .max_angle_deg = 150.0f,
         .refine_beam_center = true,
         .refine_distance_mm = false,
         .refine_detector_angles = false,