Index: trunk/psastro/src/psastro.c
===================================================================
--- trunk/psastro/src/psastro.c	(revision 10782)
+++ trunk/psastro/src/psastro.c	(revision 10833)
@@ -53,11 +53,11 @@
     }
 
-    char *mosastro = psMetadataLookupStr (NULL, config->arguments, "MOSASTRO");
-    if (mosastro == NULL) {
-        if (!psastroChipAstrom (config, refs)) {
-	    psErrorStackPrint(stderr, "failed to perform single chip astrometry\n");
-	    exit (1);
-	}
-    } else {
+    if (!psastroChipAstrom (config, refs)) {
+      psErrorStackPrint(stderr, "failed to perform single chip astrometry\n");
+      exit (1);
+    }
+
+    bool mosastro = psMetadataLookupBool (NULL, config->arguments, "MOSAIC.MODE");
+    if (!mosastro) {
 	if (!psastroMosaicAstrom (config, refs)) {
 	    psErrorStackPrint(stderr, "failed to perform mosaic camera astrometry\n");