Index: trunk/psModules/src/detrend/pmDark.c
===================================================================
--- trunk/psModules/src/detrend/pmDark.c	(revision 16823)
+++ trunk/psModules/src/detrend/pmDark.c	(revision 16824)
@@ -458,5 +458,5 @@
     } else {
         psMetadata *headers = psFitsReadHeaderSet(NULL, fits); // FITS headers
-        if (psMetadataLookup(headers, PM_DARK_FITS_EXTNAME)) {
+        if (!psMetadataLookup(headers, PM_DARK_FITS_EXTNAME)) {
             write = true;
         }