/* Specification. */
#ifdef USE_LONG_DOUBLE
/* Specification found in math.h or isnanl-nolibm.h. */
-extern int rpl_isnanl (long double x);
+extern int rpl_isnanl (long double x) _GL_ATTRIBUTE_CONST;
#elif ! defined USE_FLOAT
/* Specification found in math.h or isnand-nolibm.h. */
extern int rpl_isnand (double x);