diff --git a/rugnux/Rugnux.cpp b/rugnux/Rugnux.cpp
index 52d1d535..dc9cb468 100644
--- a/rugnux/Rugnux.cpp
+++ b/rugnux/Rugnux.cpp
@@ -1529,13 +1529,17 @@ ProcessResult Rugnux::RunPipeline(RugnuxObserver *observer, bool write_output, b
                     double sum = 0.0;
                     for (size_t j = lo; j < hi; ++j) sum += rs[j].second;
                     if (sum / static_cast<double>(hi - lo) < 1.0) {
-                        // Cut the noise-dominated high-res shells, but only when a good low-res region
-                        // exists above the cutoff. If even the lowest-res shell (b == 0) is below the
-                        // threshold - as happens for very weak data whose I/sigma is floored by the
-                        // error model although CC1/2 is still high - there is no clean/noise boundary,
-                        // and cutting here would discard essentially all reflections and leave the
-                        // re-merge with no resolution range. Leave d_min_search at 0 (no cut) instead.
-                        if (b > 0) d_min_search = rs[lo].first;
+                        // Cut the noise-dominated high-res shells. When even the lowest-res shell fails,
+                        // keep that shell alone rather than abandoning the cut. The bound is absolute
+                        // while the merged I/sigma it tests is capped by the merge's own ISa, so a merge
+                        // whose ISa has fallen below 1 cannot satisfy it in ANY shell - and that is
+                        // exactly the merge the search must not be handed whole, since the noise which
+                        // drove ISa down is what the cut exists to remove. Abandoning it feeds back:
+                        // more noise into the search, a weaker operator statistic, and a lost symmetry.
+                        if (b > 0)
+                            d_min_search = rs[lo].first;
+                        else if (per >= 400)
+                            d_min_search = rs[per - 1].first;
                         break;
                     }
                 }