--- a/libquadmath/math/nextafterq.c	Sun Aug 21 07:07:55 2011 +0900
+++ b/libquadmath/math/nextafterq.c	Fri Oct 27 22:46:09 2017 +0900
@@ -1,4 +1,4 @@
-/* s_nextafterl.c -- long double version of s_nextafter.c.
+/* nextafterq.c -- __float128 version of s_nextafter.c.
  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
  */
 
@@ -13,6 +13,7 @@
  * ====================================================
  */
 
+#include <errno.h>
 #include "quadmath-imp.h"
 
 __float128
@@ -54,9 +55,15 @@
 	    }
 	}
 	hy = hx&0x7fff000000000000LL;
-	if(hy==0x7fff000000000000LL) return x+x;/* overflow  */
+	if(hy==0x7fff000000000000LL) {
+	    __float128 u = x + x;		/* overflow  */
+	    math_force_eval (u);
+	    errno = ERANGE;
+	}
 	if(hy==0) {
-	    /* here we should raise an underflow flag */
+	    __float128 u = x*x;			/* underflow */
+	    math_force_eval (u);		/* raise underflow flag */
+	    errno = ERANGE;
 	}
 	SET_FLT128_WORDS64(x,hx,lx);
 	return x;