diff --git a/rugnux/rugnux_cli.cpp b/rugnux/rugnux_cli.cpp
index 98862ca54..d672d9a80 100644
--- a/rugnux/rugnux_cli.cpp
+++ b/rugnux/rugnux_cli.cpp
@@ -2191,19 +2191,19 @@ static int RunRugnux(int argc, char **argv) {
         const std::string poni_path = output_prefix + ".poni";
         const std::string json_path = output_prefix + ".json";
         try {
-            // A .poni file states where the detector is and nothing else. It has no field for doubt, so
-            // there is no honest way to write a geometry that is not a measurement into one - every
-            // program that reads it downstream would read it as if it were. Withholding it is the only
-            // thing the format allows. The JSON is written either way and carries the verdict, because
-            // it is where the evidence lives and it is wanted most exactly when the fit failed.
-            if (cal.converged)
-                WritePoniFile(poni_path, experiment, g);
-            // The same answer for whatever reads it next. A PONI file is what pyFAI and its neighbours
-            // take, but nothing in this system does, and it says nothing about how well the geometry is
-            // known - so write the JSON alongside it, with the geometry under dataset_settings' own
-            // property names and the quality beside it.
+            // The JSON FIRST, and ahead of anything the poni can refuse. It is the file that can state everything -
+            // the verdict, the uncertainty, and a geometry a PONI has no fields for - so it must exist
+            // even where the poni cannot be written, and it is wanted most exactly when the fit failed.
+            // WritePoniFile refuses a detector whose image orientation a PONI cannot express; refusing
+            // by throwing would otherwise take the JSON with it and leave a run whose own error text
+            // says "the .json beside it carries the full geometry" beside no .json at all.
             WriteCalibrationJson(json_path, experiment, cal, calibrant_label,
                                  calibration_method == CalibrationMethod::Rings ? "rings" : "spots");
+            // A .poni file states where the detector is and nothing else. It has no field for doubt, so
+            // there is no honest way to write a geometry that is not a measurement into one - every
+            // program that reads it downstream would read it as if it were.
+            if (cal.converged)
+                WritePoniFile(poni_path, experiment, g);
         } catch (const std::exception &e) {
             logger.Error("{}", e.what());
             return 1;