diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 9fd92dd0f..9973ccb53 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,6 +10,7 @@
 * `rugnux` writes the unmerged MTZ by default, and a P1 merge beside it, so a wrong space group can be re-merged without reprocessing.
 * Significant improvements to symmetry handling in `rugnux`: the lattice, the point group, the setting and the systematic absences.
 * The `rugnux` report gives the resolution the CC1/2 fit reached, beside the range the reflections were written to.
+* The `jfjoch_viewer` grid scan view draws the cells in the proportion of the scan steps, so the map has the shape of the scanned area.
 
 ### 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.
diff --git a/viewer/image_viewer/JFJochGridScanImage.cpp b/viewer/image_viewer/JFJochGridScanImage.cpp
index c4bfc1bda..ea6601f90 100644
--- a/viewer/image_viewer/JFJochGridScanImage.cpp
+++ b/viewer/image_viewer/JFJochGridScanImage.cpp
@@ -25,6 +25,9 @@ void JFJochGridScanImage::loadData(const std::vector<float> &data, const GridSca
 
     W = settings.GetGridSizeX_step();
     H = settings.GetGridSizeY_step();
+    // Draw a cell in the proportion of the area it covers, so a scan with a coarse x step and a
+    // fine y step looks like the sample region it was taken over, not like a square grid.
+    pixel_aspect_ = std::fabs(settings.GetGridStepY_um() / settings.GetGridStepX_um());
     image_fp = settings.Rearrange(data, NAN);
 
     std::vector<int64_t> indices(image_fp.size());
diff --git a/viewer/image_viewer/JFJochImage.cpp b/viewer/image_viewer/JFJochImage.cpp
index 39e4c21ad..72941a010 100644
--- a/viewer/image_viewer/JFJochImage.cpp
+++ b/viewer/image_viewer/JFJochImage.cpp
@@ -954,7 +954,7 @@ void JFJochImage::fitToView() {
 }
 
 void JFJochImage::fitToViewShorterSideOnce() {
-    if (initial_fit_done_ && prev_H == H && prev_W == W)
+    if (initial_fit_done_ && prev_H == H && prev_W == W && prev_aspect_ == pixel_aspect_)
         return;
 
 
@@ -963,6 +963,7 @@ void JFJochImage::fitToViewShorterSideOnce() {
 
     prev_H = H;
     prev_W = W;
+    prev_aspect_ = pixel_aspect_;
 
     // Guard against tiny or zero viewport (happens before layout settles)
     const QSize vp = viewport()->size();
@@ -976,7 +977,11 @@ void JFJochImage::fitToViewShorterSideOnce() {
     setTransformationAnchor(QGraphicsView::AnchorViewCenter);
     setTransform(QTransform());
 
-    fitInView(QRectF(0, 0, static_cast<qreal>(W), static_cast<qreal>(H)), Qt::KeepAspectRatio);
+    // Non-square pixels are fitted as if the image were as tall as they draw it, and the extra
+    // height is then put back into the transform: the image still fits, and the uniform zooms
+    // that follow keep the proportion.
+    fitInView(QRectF(0, 0, static_cast<qreal>(W), static_cast<qreal>(H) * pixel_aspect_), Qt::KeepAspectRatio);
+    scale(1.0, pixel_aspect_);
 
     scale_factor = transform().m11();
     centerOn(QPointF(static_cast<qreal>(W) * 0.5, static_cast<qreal>(H) * 0.5));
@@ -998,7 +1003,7 @@ void JFJochImage::setZoom(double input) {
         scale_factor = input;
         if (!scene())
             return;
-        setTransform(QTransform::fromScale(input, input));
+        setTransform(QTransform::fromScale(input, input * pixel_aspect_));
         updateOverlay();
         emitViewportChanged();
     }
diff --git a/viewer/image_viewer/JFJochImage.h b/viewer/image_viewer/JFJochImage.h
index b8cb6ea67..afeb7a92c 100644
--- a/viewer/image_viewer/JFJochImage.h
+++ b/viewer/image_viewer/JFJochImage.h
@@ -109,6 +109,13 @@ protected:
     size_t W = 0, H = 0;
     size_t prev_W = 0, prev_H = 0;
 
+    // Height of one pixel as it is drawn, in units of its width. 1.0 for a detector image, where
+    // pixels are square; a grid scan whose x and y steps differ sets it so that a cell is drawn
+    // in the proportion of the area it covers. Only the view transform is anisotropic - scene
+    // coordinates stay one unit per pixel everywhere.
+    qreal pixel_aspect_ = 1.0;
+    qreal prev_aspect_ = 1.0;
+
     // Track initial fit state and last image size
     bool initial_fit_done_ = false;