Index: /trunk/Mars/mcore/fits.h
===================================================================
--- /trunk/Mars/mcore/fits.h	(revision 17749)
+++ /trunk/Mars/mcore/fits.h	(revision 17750)
@@ -335,8 +335,11 @@
             if (bytes!=bytes_per_row)
             {
-#ifdef __EXCEPTIONS
-                throw std::runtime_error("Column size mismatch");
-#else
-                gLog << ___err___ << "ERROR - Column size mismatch" << std::endl;
+                std::ostringstream str;
+                str << "Sum of bytes in columns [" << bytes << "] does not match (Z)NAXIS2 [" << bytes_per_row << "].";
+
+#ifdef __EXCEPTIONS
+                throw std::runtime_error(str.str());
+#else
+                gLog << ___err___ << "ERROR - " << str.str() << std::endl;
                 return;
 #endif