Index: trunk/Mars/mcore/fits.h
===================================================================
--- trunk/Mars/mcore/fits.h	(revision 16898)
+++ trunk/Mars/mcore/fits.h	(revision 16935)
@@ -285,5 +285,5 @@
 
             const string tFormName = is_compressed ? "ZFORM" : "TFORM";
-            for (size_t i=1; i<=num_cols; i++)
+            for (long long unsigned int i=1; i<=num_cols; i++)
             {
                 const string num(to_string(i));