Index: trunk/psphot/src/psphotSignificanceImage.c
===================================================================
--- trunk/psphot/src/psphotSignificanceImage.c	(revision 26894)
+++ trunk/psphot/src/psphotSignificanceImage.c	(revision 28667)
@@ -76,5 +76,11 @@
     // Calculate correction factor for the covariance produced by the (potentially multiple) smoothing
     psKernel *kernel = psImageSmoothKernel(SIGMA_SMTH, NSIGMA_SMTH); // Kernel used for smoothing
-    float factor = 1.0 / psImageCovarianceCalculateFactor(kernel, readout->covariance);
+    double sum2 = 0.0;                                               // Sum of kernel squared
+    for (int y = kernel->yMin; y <= kernel->yMax; y++) {
+        for (int x = kernel->xMin; x <= kernel->xMax; x++) {
+            sum2 += PS_SQR(kernel->kernel[y][x]);
+        }
+    }
+    float factor = 1.0 / (sum2 * psImageCovarianceCalculateFactor(kernel, readout->covariance));
     psFree(kernel);