diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index dfcc7b37..b3bb229d 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -3,6 +3,7 @@
 ### 1.0.0-rc.165
 This is an UNSTABLE release. It includes many experimental features, as well as many AI generated fixes. We recommend using rc.152 for production use.
 
+* `MEAN_ATOM_DENSITY_SIGMA`, the mean 2Fo-Fc density at the model's atom centres that `rugnux --model` reports, is read from the map by cubic rather than linear interpolation and comes out around a tenth higher as a result. The map, the R-factors and every other number are unchanged; only this reading of the map moves, so it is no longer comparable with the figure earlier versions printed.
 * `rugnux --model` writes an anomalous difference map (`<prefix>_anom.ccp4`) when the merge kept the Bijvoet split, and names the ten model atoms it peaks highest on - `ANOMALOUS_SITE_01`..`_10` in the results report, and one line in the log - so a run says which atoms carry the anomalous signal and how many sigma each one is.
 * The rugnux results report records how the run was invoked, what it cost and what it ran on: `COMMAND_LINE=` is the command line as one shell-ready line, `WALL_TIME=` the whole invocation in seconds, and `GPU_COUNT=` / `GPU=` how many GPUs were visible and which ones. The total wall time is also printed on stdout, next to the processing time it is slightly larger than.
 * The rugnux results report has a `10. MODEL VALIDATION` section when `--model` was given: R-work / R-free with their reflection counts, the bulk-solvent and scale parameters, the mean 2Fo-Fc density at the atom centres, the reindexing operators and where the maps were written - or `MODEL_VALIDATION= NOT_PERFORMED` and the reason, when the model could not be used. `REPORT_VERSION` is 4; `WARNINGS` moves from section 10 to 11 and no existing key changed.
diff --git a/rugnux/ModelValidation.cpp b/rugnux/ModelValidation.cpp
index 1072650d..3387c94d 100644
--- a/rugnux/ModelValidation.cpp
+++ b/rugnux/ModelValidation.cpp
@@ -49,6 +49,11 @@ double write_ccp4(const gemmi::Grid<float> &map, const std::string &path) {
     return ccp4.hstats.rms;
 }
 
+// Cubic, not the default linear, for reading a map at a point. The maps are sampled every d_min/3,
+// and a peak that sharp read by trilinear interpolation comes out up to a quarter low - unevenly
+// enough to reorder the anomalous sites.
+constexpr int MAP_INTERPOLATION_ORDER = 3;
+
 // How many anomalous sites the report names. The strongest few are what says whether the anomalous
 // signal is there and what carries it; a full site list is what the map file is for.
 constexpr size_t MAX_ANOMALOUS_SITES = 10;
@@ -285,7 +290,7 @@ ModelValidationResult ValidateAgainstModel(const std::vector<MergedReflection> &
         for (gemmi::Model &m : st.models)
             for (gemmi::Chain &ch : m.chains)
                 for (gemmi::Residue &r : ch.residues)
-                    for (gemmi::Atom &a : r.atoms) { s += grid2fofc.interpolate_value(a.pos); ++n; }
+                    for (gemmi::Atom &a : r.atoms) { s += grid2fofc.interpolate_value(a.pos, MAP_INTERPOLATION_ORDER); ++n; }
         result.mean_atom_density_sigma = (n > 0 && rms2 > 0) ? (s / n) / rms2 : 0;
     }
 
@@ -347,12 +352,10 @@ ModelValidationResult ValidateAgainstModel(const std::vector<MergedReflection> &
                         for (gemmi::Atom &a : r.atoms) {
                             if (a.is_hydrogen())   // hydrogen scatters no anomalous signal
                                 continue;
-                            // Cubic, not the default linear: the map is sampled every d_min/3, and a
-                            // peak that sharp read by trilinear interpolation comes out up to a quarter
-                            // low - unevenly enough to reorder the sites.
                             sites.push_back({fmt::format("{} {} {}{}", a.name, r.name, ch.name,
                                                          r.seqid.str()),
-                                             rms > 0 ? grid.interpolate_value(a.pos, 3) / rms : 0.0});
+                                             rms > 0 ? grid.interpolate_value(a.pos, MAP_INTERPOLATION_ORDER) / rms
+                                                     : 0.0});
                         }
             std::sort(sites.begin(), sites.end(),
                       [](const auto &x, const auto &y) { return x.sigma > y.sigma; });