diff --git a/rtengine/iptransform.cc b/rtengine/iptransform.cc
index 3d384ee62..595112735 100644
--- a/rtengine/iptransform.cc
+++ b/rtengine/iptransform.cc
@@ -1244,6 +1244,25 @@ void ImProcFunctions::transformGeneral(bool highQuality, Imagefloat *original, I
                 pLCPMap->correctDistortion(x_d, y_d, w2, h2);
             }
 
+            // Hard-coded fisheye undistortion for testing purposes.
+            bool enableFish = true;
+            // Hard-coded focal length so it matches the image used for testing
+            double focal_source = maxRadius*1351.0/5206.416;
+            // A different destination focal length allows the user to shrink the image so more of the original FoV fits into the undistorted image.
+            // fish_scale = 0.5 means the source image is downscaled by a factor of two in the center.
+            double fish_scale = 0.5;
+            double focal_dst = focal_source*fish_scale;
+            if (enableFish) {
+                x_d /= focal_dst;
+                y_d /= focal_dst;
+
+                double const r = std::sqrt(x_d*x_d + y_d*y_d);
+                double const factor = focal_source * std::atan(r)/r;
+
+                x_d *= factor;
+                y_d *= factor;
+            }
+
             // rotate
             const double Dxc = x_d * cost - y_d * sint;
             const double Dyc = x_d * sint + y_d * cost;