--- a/liboctave/mach-info.h
+++ b/liboctave/mach-info.h
@@ -28,6 +28,10 @@
 class
 oct_mach_info
 {
+protected:
+
+  oct_mach_info (void);
+
 public:
 
   enum float_format
@@ -41,7 +45,7 @@
       cray
     };
 
-  oct_mach_info (void);
+  static bool instance_ok (void);
 
   static float_format native_float_format (void);
 
@@ -57,15 +61,15 @@
 
   static oct_mach_info *instance;
 
-  void init_float_format (void);
+  void init_float_format (void) const;
 
-  void ten_little_endians (void);
+  void ten_little_endians (void) const;
 
   // The floating point format for the current machine.
-  float_format native_float_fmt;
+  mutable float_format native_float_fmt;
 
   // TRUE if the byte order on this system is big endian.
-  bool big_chief;
+  mutable bool big_chief;
 
   // No copying!