diff --git a/rugnux/rugnux_cli.cpp b/rugnux/rugnux_cli.cpp
index bfdc3224..bc138536 100644
--- a/rugnux/rugnux_cli.cpp
+++ b/rugnux/rugnux_cli.cpp
@@ -69,7 +69,7 @@ void print_usage() {
     std::cout << "   --adaptive-spots                 Self-calibrating detection (DEFAULT): the strong-pixel threshold comes from each image's own per-resolution-ring noise instead of the fixed --spot-threshold, so one setting adapts across datasets (no per-dataset --spot-threshold/--spot-sigma tuning)." << std::endl;
     std::cout << "   --no-adaptive-spots              Turn adaptive detection off and use the fixed --spot-threshold / --spot-sigma finder instead" << std::endl;
     std::cout << "   --spot-false-pixels <num>        Adaptive detection operating point: expected noise pixels tolerated per frame (default: 100; implies --adaptive-spots)" << std::endl;
-    std::cout << "   --spot-high-resolution <num>     High resolution limit for spot finding. If omitted, stills extend as far as the detector reaches (no resolution clipping) and rotation data keeps a 1.5 A limit." << std::endl;
+    std::cout << "   --spot-high-resolution <num>     High resolution limit for spot finding. If omitted, stills extend as far as the detector reaches (no resolution clipping) and rotation data keeps a 1.5 A limit; give 0 for no limit on either." << std::endl;
     std::cout << "   --spot-low-resolution <num>      Low resolution limit for spot finding, in A (default: 50; lower it, e.g. 24, to exclude the direct-beam halo on weakly-diffracting serial data)" << std::endl;
     std::cout << "   --max-spots <num>                Max spot count (default: 250)" << std::endl;
     std::cout << "   --detect-ice-rings[=on|off]      Flag ice-ring spots (de-prioritised in indexing) and exclude ice-ring reflections from scaling/merging; overrides the dataset/master-file setting (default: use dataset value)" << std::endl;
@@ -542,6 +542,9 @@ int main(int argc, char **argv) {
     GeomRefinementAlgorithmEnum refinement_algorithm = GeomRefinementAlgorithmEnum::BeamCenter;
 
     std::optional<float> d_min_spot_finding;    // unset -> as far as the detector reaches
+    // Whether --spot-high-resolution was given at all. Unset covers two different requests - "the user
+    // said nothing", where rotation applies its own default, and "the user asked for no limit".
+    bool d_min_spot_finding_given = false;
     float d_max_spot_finding = 0;   // 0 = keep the SpotFindingSettings default (50 A)
     std::optional<float> d_min_scale_merge;
     std::optional<ResolutionCutoffMethod> resolution_cutoff_method;   // --resolution-cutoff cc-logistic|off
@@ -769,6 +772,7 @@ int main(int argc, char **argv) {
             // optional the rest of the code understands. Passing the 0 through instead reached
             // ResolutionShells (via the spot plot), which rejects a zero d_min and threw away every image.
             const auto d_min = parse_number_arg<float>(optarg, "--spot-high-resolution", logger, 0.0f);
+            d_min_spot_finding_given = true;
             if (d_min > 0.0f) {
                 d_min_spot_finding = d_min;
                 logger.Info("High resolution limit for spot finding set to {:.2f} A", d_min);
@@ -1504,7 +1508,7 @@ int main(int argc, char **argv) {
     spot_settings.min_pix_per_spot = min_pix_per_spot;
     if (rotation_indexing && !spot_settings.min_pix_per_spot.has_value())
         spot_settings.min_pix_per_spot = 2;
-    if (rotation_indexing && !d_min_spot_finding.has_value())
+    if (rotation_indexing && !d_min_spot_finding.has_value() && !d_min_spot_finding_given)
         d_min_spot_finding = 1.5f;
     spot_settings.adaptive_threshold = adaptive_spots.value_or(true);
     spot_settings.high_resolution_limit = d_min_spot_finding;