diff --git a/gcc/config/mips/iris5.h b/gcc/config/mips/iris5.h
index 879fe3934c7..62703a15896 100644
--- a/gcc/config/mips/iris5.h
+++ b/gcc/config/mips/iris5.h
@@ -91,7 +91,12 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #undef ASM_FINAL_SPEC
 
 /* The system header files are C++ aware. */
-#define NO_IMPLICIT_EXTERN_C 1
+/* ??? Unfortunately, most but not all of the headers are C++ aware.
+   Specifically, curses.h is not, and libg++ won't build because of it
+   if this is defined.  On the other hand, SGI has C++ packages with
+   header files in /usr/include, and they won't work unless this is
+   defined.  We need some way to fix just those files that need fixing.  */
+/* #define NO_IMPLICIT_EXTERN_C 1 */
 
 /* We don't support debugging info for now. */
 #undef DBX_DEBUGGING_INFO