diff --git a/stdlib/strtod_nan.c b/stdlib/strtod_nan.c
index f64fec1897..c5876b59a0 100644
--- a/stdlib/strtod_nan.c
+++ b/stdlib/strtod_nan.c
@@ -18,7 +18,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <strtod_nan_narrow.h>
-#include <strtod_nan_double.h>
+#include <math-type-macros-double.h>
 
 #define STRTOD_NAN __strtod_nan
 #include <strtod_nan_main.c>
diff --git a/stdlib/strtof_nan.c b/stdlib/strtof_nan.c
index ea3decb729..f085c5b4fb 100644
--- a/stdlib/strtof_nan.c
+++ b/stdlib/strtof_nan.c
@@ -18,7 +18,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <strtod_nan_narrow.h>
-#include <strtod_nan_float.h>
+#include <math-type-macros-float.h>
 
 #define STRTOD_NAN __strtof_nan
 #include <strtod_nan_main.c>
diff --git a/stdlib/strtold_nan.c b/stdlib/strtold_nan.c
index d4bbcc0a8b..eadfe546e2 100644
--- a/stdlib/strtold_nan.c
+++ b/stdlib/strtold_nan.c
@@ -23,7 +23,7 @@
    representation.  */
 #ifndef __NO_LONG_DOUBLE_MATH
 # include <strtod_nan_narrow.h>
-# include <strtod_nan_ldouble.h>
+# include <math-type-macros-ldouble.h>
 
 # define STRTOD_NAN __strtold_nan
 # include <strtod_nan_main.c>
diff --git a/stdlib/strtod_nan_double.h b/sysdeps/generic/math-mantissa-double.h
similarity index 92%
rename from stdlib/strtod_nan_double.h
rename to sysdeps/generic/math-mantissa-double.h
+++ b/sysdeps/generic/math-mantissa-double.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For double.
+/* Mantissa handling for double.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define FLOAT		double
 #define SET_MANTISSA(flt, mant)				\
   do							\
     {							\
diff --git a/stdlib/strtod_nan_float.h b/sysdeps/generic/math-mantissa-float.h
similarity index 92%
rename from stdlib/strtod_nan_float.h
rename to sysdeps/generic/math-mantissa-float.h
+++ b/sysdeps/generic/math-mantissa-float.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For float.
+/* Mantissa handling for float.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define	FLOAT		float
 #define SET_MANTISSA(flt, mant)			\
   do						\
     {						\
diff --git a/sysdeps/generic/math-type-macros-double.h b/sysdeps/generic/math-type-macros-double.h
index 1af4c74e4b..f2c569c63b 100644
--- a/sysdeps/generic/math-type-macros-double.h
+++ b/sysdeps/generic/math-type-macros-double.h
@@ -27,6 +27,7 @@
 #define CFLOAT _Complex double
 #define M_STRTO_NAN __strtod_nan
 
+#include <math-mantissa-double.h>
 #include <libm-alias-double.h>
 
 #ifndef declare_mgen_alias
@@ -42,7 +43,7 @@
 
 /* Do not use the type-generic wrapper templates if compatibility with
    SVID error handling is needed.  */
-#include <math-svid-compat.h>
+#include <math/math-svid-compat.h>
 #define __USE_WRAPPER_TEMPLATE !LIBM_SVID_COMPAT
 
 #endif
diff --git a/sysdeps/generic/math-type-macros-float.h b/sysdeps/generic/math-type-macros-float.h
index 9273bdee0e..fc2bc736f7 100644
--- a/sysdeps/generic/math-type-macros-float.h
+++ b/sysdeps/generic/math-type-macros-float.h
@@ -30,6 +30,7 @@
    the double macro constants.  */
 #define M_MLIT(c) c
 
+#include <math-mantissa-float.h>
 #include <libm-alias-float.h>
 
 #ifndef declare_mgen_alias
@@ -45,7 +46,7 @@
 
 /* Do not use the type-generic wrapper templates if compatibility with
    SVID error handling is needed.  */
-#include <math-svid-compat.h>
+#include <math/math-svid-compat.h>
 #define __USE_WRAPPER_TEMPLATE !LIBM_SVID_COMPAT
 
 #endif
diff --git a/sysdeps/generic/math-type-macros-float128.h b/sysdeps/generic/math-type-macros-float128.h
index 485c13bb88..f2ce3c5a92 100644
--- a/sysdeps/generic/math-type-macros-float128.h
+++ b/sysdeps/generic/math-type-macros-float128.h
@@ -29,6 +29,7 @@
 
 #define M_MLIT(c) c ## f128
 
+#include <math-mantissa-float128.h>
 #include <libm-alias-float128.h>
 
 #ifndef declare_mgen_alias
diff --git a/sysdeps/generic/math-type-macros-ldouble.h b/sysdeps/generic/math-type-macros-ldouble.h
index 5fe1600231..a4f577099c 100644
--- a/sysdeps/generic/math-type-macros-ldouble.h
+++ b/sysdeps/generic/math-type-macros-ldouble.h
@@ -27,6 +27,7 @@
 #define CFLOAT _Complex long double
 #define M_STRTO_NAN __strtold_nan
 
+#include <math-mantissa-ldouble.h>
 #include <libm-alias-ldouble.h>
 
 #ifndef declare_mgen_alias
@@ -42,7 +43,7 @@
 
 /* Do not use the type-generic wrapper templates if compatibility with
    SVID error handling is needed.  */
-#include <math-svid-compat.h>
+#include <math/math-svid-compat.h>
 #define __USE_WRAPPER_TEMPLATE !LIBM_SVID_COMPAT
 
 #endif
diff --git a/sysdeps/generic/math-type-macros.h b/sysdeps/generic/math-type-macros.h
index ffcf7b80b6..330ea64d25 100644
--- a/sysdeps/generic/math-type-macros.h
+++ b/sysdeps/generic/math-type-macros.h
@@ -40,7 +40,10 @@
 
   declare_mgen_alias_r(from,to)
       This exposes the appropriate symbol(s) for a
-      function f_r of type FLOAT.  */
+      function f_r of type FLOAT.
+
+  SET_MANTISSA(flt, mant)
+      Set the variable FLT of type FLOAT to the mantissa MANT.  */
 
 #ifndef M_PFX
 # error "M_PFX must be defined."
@@ -66,6 +69,9 @@
 #ifndef declare_mgen_alias_r
 # error "declare_mgen_alias_r must be defined."
 #endif
+#ifndef SET_MANTISSA
+# error "SET_MANTISSA must be defined."
+#endif
 
 #define __M_CONCAT(a,b) a ## b
 #define __M_CONCATX(a,b) __M_CONCAT(a,b)
diff --git a/sysdeps/ieee754/float128/strtod_nan_float128.h b/sysdeps/ieee754/float128/math-mantissa-float128.h
similarity index 92%
rename from sysdeps/ieee754/float128/strtod_nan_float128.h
rename to sysdeps/ieee754/float128/math-mantissa-float128.h
+++ b/sysdeps/ieee754/float128/math-mantissa-float128.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For _Float128.
+/* Mantissa handling for _Float128.
    Copyright (C) 2017-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,8 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define FLOAT		_Float128
+#include <ieee754_float128.h>
+
 #define SET_MANTISSA(flt, mant)				\
   do							\
     {							\
diff --git a/sysdeps/ieee754/float128/strtof128_nan.c b/sysdeps/ieee754/float128/strtof128_nan.c
index 36a9bfffed..37a7f4e02e 100644
--- a/sysdeps/ieee754/float128/strtof128_nan.c
+++ b/sysdeps/ieee754/float128/strtof128_nan.c
@@ -19,10 +19,8 @@
 
 #include <math.h>
 
-#include <float128_private.h>
-
 #include <strtod_nan_narrow.h>
-#include <strtod_nan_float128.h>
+#include <math-type-macros-float128.h>
 
 #define STRTOD_NAN __strtof128_nan
 #include <stdlib/strtod_nan_main.c>
diff --git a/sysdeps/ieee754/float128/wcstof128_nan.c b/sysdeps/ieee754/float128/wcstof128_nan.c
index ffc72a016a..f504809dcf 100644
--- a/sysdeps/ieee754/float128/wcstof128_nan.c
+++ b/sysdeps/ieee754/float128/wcstof128_nan.c
@@ -18,7 +18,6 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <stdlib/strtod_nan_wide.h>
-#include <float128_private.h>
-#include <strtod_nan_float128.h>
+#include <math-type-macros-float128.h>
 #define STRTOD_NAN __wcstof128_nan
 #include <stdlib/strtod_nan_main.c>
diff --git a/sysdeps/ieee754/ldbl-128/strtod_nan_ldouble.h b/sysdeps/ieee754/ldbl-128/math-mantissa-ldouble.h
similarity index 92%
rename from sysdeps/ieee754/ldbl-128/strtod_nan_ldouble.h
rename to sysdeps/ieee754/ldbl-128/math-mantissa-ldouble.h
+++ b/sysdeps/ieee754/ldbl-128/math-mantissa-ldouble.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For ldbl-128.
+/* Mantissa handling for ldbl-128.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define FLOAT		long double
 #define SET_MANTISSA(flt, mant)				\
   do							\
     {							\
diff --git a/sysdeps/ieee754/ldbl-128ibm/strtod_nan_ldouble.h b/sysdeps/ieee754/ldbl-128ibm/math-mantissa-ldouble.h
similarity index 91%
rename from sysdeps/ieee754/ldbl-128ibm/strtod_nan_ldouble.h
rename to sysdeps/ieee754/ldbl-128ibm/math-mantissa-ldouble.h
+++ b/sysdeps/ieee754/ldbl-128ibm/math-mantissa-ldouble.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For ldbl-128ibm.
+/* Mantissa handling or ldbl-128ibm.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define FLOAT		long double
 #define SET_MANTISSA(flt, mant)					\
   do								\
     {								\
diff --git a/sysdeps/ieee754/ldbl-96/strtod_nan_ldouble.h b/sysdeps/ieee754/ldbl-96/math-mantissa-ldouble.h
similarity index 91%
rename from sysdeps/ieee754/ldbl-96/strtod_nan_ldouble.h
rename to sysdeps/ieee754/ldbl-96/math-mantissa-ldouble.h
+++ b/sysdeps/ieee754/ldbl-96/math-mantissa-ldouble.h
@@ -1,4 +1,4 @@
-/* Convert string for NaN payload to corresponding NaN.  For ldbl-96.
+/* Mantissa handling for ldbl-96.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define FLOAT		long double
 #define SET_MANTISSA(flt, mant)				\
   do							\
     {							\
diff --git a/wcsmbs/wcstod_nan.c b/wcsmbs/wcstod_nan.c
index 1aee82d844..1423f3e8aa 100644
--- a/wcsmbs/wcstod_nan.c
+++ b/wcsmbs/wcstod_nan.c
@@ -17,7 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include "../stdlib/strtod_nan_wide.h"
-#include "../stdlib/strtod_nan_double.h"
+#include <math-type-macros-double.h>
 
 #define STRTOD_NAN __wcstod_nan
 #include "../stdlib/strtod_nan_main.c"
diff --git a/wcsmbs/wcstof_nan.c b/wcsmbs/wcstof_nan.c
index 9c89e24370..96f2198667 100644
--- a/wcsmbs/wcstof_nan.c
+++ b/wcsmbs/wcstof_nan.c
@@ -17,7 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include "../stdlib/strtod_nan_wide.h"
-#include "../stdlib/strtod_nan_float.h"
+#include <math-type-macros-float.h>
 
 #define STRTOD_NAN __wcstof_nan
 #include "../stdlib/strtod_nan_main.c"
diff --git a/wcsmbs/wcstold_nan.c b/wcsmbs/wcstold_nan.c
index a4d274f37f..66793ec459 100644
--- a/wcsmbs/wcstold_nan.c
+++ b/wcsmbs/wcstold_nan.c
@@ -23,7 +23,7 @@
    representation.  */
 #ifndef __NO_LONG_DOUBLE_MATH
 # include "../stdlib/strtod_nan_wide.h"
-# include <strtod_nan_ldouble.h>
+# include <math-type-macros-ldouble.h>
 
 # define STRTOD_NAN __wcstold_nan
 # include "../stdlib/strtod_nan_main.c"
