Index: trunk/psModules/src/objects/pmPCMdata.c
===================================================================
--- trunk/psModules/src/objects/pmPCMdata.c	(revision 32725)
+++ trunk/psModules/src/objects/pmPCMdata.c	(revision 33442)
@@ -136,4 +136,18 @@
 	    sum += value;
 	}
+    }
+
+    if (!(sum > 0.0)) {
+        // Crazy PSF image print out some debugging information ...
+        fprintf(stderr, "invalid kernel sum %f found by pmPCMkernelFromPSF\n", sum);    for (int j = psf->yMin; j <= psf->yMax; j++) {
+            fprintf(stderr, "Row %d\n", j);
+            for (int i = psf->xMin; i <= psf->xMax; i++) {
+                double value = source->psfImage->data.F32[y0 + j][x0 + i];
+                fprintf(stderr, "  %d %f\n", i, value);
+            }
+        }
+        fflush(stderr);
+        // ... but avoid the asssertion two lines down by escaping
+        goto escape;
     }
     assert (sum > 0.0);