diff --git a/newlib/libc/ctype/ctype_.h b/newlib/libc/ctype/ctype_.h
index a73870b3e..42ad2c870 100644
--- a/newlib/libc/ctype/ctype_.h
+++ b/newlib/libc/ctype/ctype_.h
@@ -1,5 +1,15 @@
 #include <ctype.h>
 
+/* Define some short names to keep internal files shorter.  */
+#define _U _ISupper
+#define _L _ISlower
+#define _N _ISdigit
+#define _S _ISspace
+#define _P _ISpunct
+#define _C _IScntrl
+#define _X _ISxdigit
+#define _B _ISblank
+
 #if (defined(__GNUC__) && !defined(__CHAR_UNSIGNED__) && !defined(COMPACT_CTYPE)) || defined (__CYGWIN__)
 #define ALLOW_NEGATIVE_CTYPE_INDEX
 #endif
diff --git a/newlib/libc/ctype/isalnum.c b/newlib/libc/ctype/isalnum.c
index d926f97b7..3ddf0d2e1 100644
--- a/newlib/libc/ctype/isalnum.c
+++ b/newlib/libc/ctype/isalnum.c
@@ -46,5 +46,5 @@ No OS subroutines are required.
 int
 isalnum (int c)
 {
-	return(__CTYPE_PTR[c+1] & (_U|_L|_N));
+	return(__CTYPE_PTR[c+1] & (_ISupper|_ISlower|_ISdigit));
 }
diff --git a/newlib/libc/ctype/isalnum_l.c b/newlib/libc/ctype/isalnum_l.c
index dcb7e3652..e3587f1b2 100644
--- a/newlib/libc/ctype/isalnum_l.c
+++ b/newlib/libc/ctype/isalnum_l.c
@@ -6,5 +6,5 @@
 int
 isalnum_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & (_U|_L|_N);
+  return __locale_ctype_ptr_l (locale)[c+1] & (_ISupper|_ISlower|_ISdigit);
 }
diff --git a/newlib/libc/ctype/isalpha.c b/newlib/libc/ctype/isalpha.c
index 8b8e78a29..c8de62cea 100644
--- a/newlib/libc/ctype/isalpha.c
+++ b/newlib/libc/ctype/isalpha.c
@@ -45,5 +45,5 @@ No supporting OS subroutines are required.
 int
 isalpha (int c)
 {
-	return(__CTYPE_PTR[c+1] & (_U|_L));
+	return(__CTYPE_PTR[c+1] & (_ISupper|_ISlower));
 }
diff --git a/newlib/libc/ctype/isalpha_l.c b/newlib/libc/ctype/isalpha_l.c
index dcae3ccb4..6ff1e3b68 100644
--- a/newlib/libc/ctype/isalpha_l.c
+++ b/newlib/libc/ctype/isalpha_l.c
@@ -6,5 +6,5 @@
 int
 isalpha_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & (_U|_L);
+  return __locale_ctype_ptr_l (locale)[c+1] & (_ISupper|_ISlower);
 }
diff --git a/newlib/libc/ctype/isblank.c b/newlib/libc/ctype/isblank.c
index 0ebc2192c..2fa29f33f 100644
--- a/newlib/libc/ctype/isblank.c
+++ b/newlib/libc/ctype/isblank.c
@@ -44,5 +44,5 @@ No supporting OS subroutines are required.
 int
 isblank (int c)
 {
-	return ((__CTYPE_PTR[c+1] & _B) || (c == '\t'));
+	return ((__CTYPE_PTR[c+1] & _ISblank) || (c == '\t'));
 }
diff --git a/newlib/libc/ctype/isblank_l.c b/newlib/libc/ctype/isblank_l.c
index 8bbb84e1f..6aff2f7fc 100644
--- a/newlib/libc/ctype/isblank_l.c
+++ b/newlib/libc/ctype/isblank_l.c
@@ -6,5 +6,5 @@
 int
 isblank_l (int c, struct __locale_t *locale)
 {
-  return (__locale_ctype_ptr_l (locale)[c+1] & _B) || (c == '\t');
+  return (__locale_ctype_ptr_l (locale)[c+1] & _ISblank) || (c == '\t');
 }
diff --git a/newlib/libc/ctype/iscntrl.c b/newlib/libc/ctype/iscntrl.c
index ebbdd7371..bd99ebafb 100644
--- a/newlib/libc/ctype/iscntrl.c
+++ b/newlib/libc/ctype/iscntrl.c
@@ -48,5 +48,5 @@ No supporting OS subroutines are required.
 int
 iscntrl (int c)
 {
-	return(__CTYPE_PTR[c+1] & _C);
+	return(__CTYPE_PTR[c+1] & _IScntrl);
 }
diff --git a/newlib/libc/ctype/iscntrl_l.c b/newlib/libc/ctype/iscntrl_l.c
index 0ae17c7f7..85f4d6900 100644
--- a/newlib/libc/ctype/iscntrl_l.c
+++ b/newlib/libc/ctype/iscntrl_l.c
@@ -6,5 +6,5 @@
 int
 iscntrl_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & _C;
+  return __locale_ctype_ptr_l (locale)[c+1] & _IScntrl;
 }
diff --git a/newlib/libc/ctype/isdigit.c b/newlib/libc/ctype/isdigit.c
index a5c511964..911781df3 100644
--- a/newlib/libc/ctype/isdigit.c
+++ b/newlib/libc/ctype/isdigit.c
@@ -47,5 +47,5 @@ No supporting OS subroutines are required.
 int
 isdigit (int c)
 {
-	return(__CTYPE_PTR[c+1] & _N);
+	return(__CTYPE_PTR[c+1] & _ISdigit);
 }
diff --git a/newlib/libc/ctype/isdigit_l.c b/newlib/libc/ctype/isdigit_l.c
index 1fb79e000..6e24c100c 100644
--- a/newlib/libc/ctype/isdigit_l.c
+++ b/newlib/libc/ctype/isdigit_l.c
@@ -6,5 +6,5 @@
 int
 isdigit_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & _N;
+  return __locale_ctype_ptr_l (locale)[c+1] & _ISdigit;
 }
diff --git a/newlib/libc/ctype/islower.c b/newlib/libc/ctype/islower.c
index 2b3440489..c45c6c8ad 100644
--- a/newlib/libc/ctype/islower.c
+++ b/newlib/libc/ctype/islower.c
@@ -45,5 +45,5 @@ No supporting OS subroutines are required.
 int
 islower (int c)
 {
-	return ((__CTYPE_PTR[c+1] & (_U|_L)) == _L);
+	return ((__CTYPE_PTR[c+1] & (_ISupper|_ISlower)) == _ISlower);
 }
diff --git a/newlib/libc/ctype/islower_l.c b/newlib/libc/ctype/islower_l.c
index d1f3a82d8..1c66ab48b 100644
--- a/newlib/libc/ctype/islower_l.c
+++ b/newlib/libc/ctype/islower_l.c
@@ -6,5 +6,5 @@
 int
 islower_l (int c, struct __locale_t *locale)
 {
-  return (__locale_ctype_ptr_l (locale)[c+1] & (_U|_L)) == _L;
+  return (__locale_ctype_ptr_l (locale)[c+1] & (_ISupper|_ISlower)) == _ISlower;
 }
diff --git a/newlib/libc/ctype/isprint.c b/newlib/libc/ctype/isprint.c
index e34fbe28a..7206047fb 100644
--- a/newlib/libc/ctype/isprint.c
+++ b/newlib/libc/ctype/isprint.c
@@ -59,7 +59,7 @@ No supporting OS subroutines are required.
 int
 isgraph (int c)
 {
-	return(__CTYPE_PTR[c+1] & (_P|_U|_L|_N));
+	return(__CTYPE_PTR[c+1] & (_ISpunct|_ISupper|_ISlower|_ISdigit));
 }
 
 
@@ -67,5 +67,5 @@ isgraph (int c)
 int
 isprint (int c)
 {
-	return(__CTYPE_PTR[c+1] & (_P|_U|_L|_N|_B));
+	return(__CTYPE_PTR[c+1] & (_ISpunct|_ISupper|_ISlower|_ISdigit|_ISblank));
 }
diff --git a/newlib/libc/ctype/isprint_l.c b/newlib/libc/ctype/isprint_l.c
index 535504f14..3efaa2f90 100644
--- a/newlib/libc/ctype/isprint_l.c
+++ b/newlib/libc/ctype/isprint_l.c
@@ -6,7 +6,7 @@
 int
 isgraph_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & (_P|_U|_L|_N);
+  return __locale_ctype_ptr_l (locale)[c+1] & (_ISpunct|_ISupper|_ISlower|_ISdigit);
 }
 
 #undef isprint_l
@@ -14,5 +14,5 @@ isgraph_l (int c, struct __locale_t *locale)
 int
 isprint_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & (_P|_U|_L|_N|_B);
+  return __locale_ctype_ptr_l (locale)[c+1] & (_ISpunct|_ISupper|_ISlower|_ISdigit|_ISblank);
 }
diff --git a/newlib/libc/ctype/ispunct.c b/newlib/libc/ctype/ispunct.c
index 9c5a3fcca..35f7cc2d4 100644
--- a/newlib/libc/ctype/ispunct.c
+++ b/newlib/libc/ctype/ispunct.c
@@ -47,5 +47,5 @@ No supporting OS subroutines are required.
 int
 ispunct (int c)
 {
-	return(__CTYPE_PTR[c+1] & _P);
+	return(__CTYPE_PTR[c+1] & _ISpunct);
 }
diff --git a/newlib/libc/ctype/ispunct_l.c b/newlib/libc/ctype/ispunct_l.c
index eeba1f5ae..30c2b48d6 100644
--- a/newlib/libc/ctype/ispunct_l.c
+++ b/newlib/libc/ctype/ispunct_l.c
@@ -6,6 +6,6 @@
 int
 ispunct_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & _P;
+  return __locale_ctype_ptr_l (locale)[c+1] & _ISpunct;
 }
 
diff --git a/newlib/libc/ctype/isspace.c b/newlib/libc/ctype/isspace.c
index 0def2c0ce..8834d1901 100644
--- a/newlib/libc/ctype/isspace.c
+++ b/newlib/libc/ctype/isspace.c
@@ -46,5 +46,5 @@ No supporting OS subroutines are required.
 int
 isspace (int c)
 {
-	return(__CTYPE_PTR[c+1] & _S);
+	return(__CTYPE_PTR[c+1] & _ISspace);
 }
diff --git a/newlib/libc/ctype/isspace_l.c b/newlib/libc/ctype/isspace_l.c
index bf4a36c3e..06227c87a 100644
--- a/newlib/libc/ctype/isspace_l.c
+++ b/newlib/libc/ctype/isspace_l.c
@@ -6,6 +6,6 @@
 int
 isspace_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & _S;
+  return __locale_ctype_ptr_l (locale)[c+1] & _ISspace;
 }
 
diff --git a/newlib/libc/ctype/isupper.c b/newlib/libc/ctype/isupper.c
index aeed383ec..7d916d9f3 100644
--- a/newlib/libc/ctype/isupper.c
+++ b/newlib/libc/ctype/isupper.c
@@ -43,5 +43,5 @@ No supporting OS subroutines are required.
 int
 isupper (int c)
 {
-	return ((__CTYPE_PTR[c+1] & (_U|_L)) == _U);
+	return ((__CTYPE_PTR[c+1] & (_ISupper|_ISlower)) == _ISupper);
 }
diff --git a/newlib/libc/ctype/isupper_l.c b/newlib/libc/ctype/isupper_l.c
index eb473a7a1..1fdcf1072 100644
--- a/newlib/libc/ctype/isupper_l.c
+++ b/newlib/libc/ctype/isupper_l.c
@@ -6,6 +6,6 @@
 int
 isupper_l (int c, struct __locale_t *locale)
 {
-  return (__locale_ctype_ptr_l (locale)[c+1] & (_U|_L)) == _U;
+  return (__locale_ctype_ptr_l (locale)[c+1] & (_ISupper|_ISlower)) == _ISupper;
 }
 
diff --git a/newlib/libc/ctype/isxdigit.c b/newlib/libc/ctype/isxdigit.c
index 2bfe18dbf..fb2a59ea8 100644
--- a/newlib/libc/ctype/isxdigit.c
+++ b/newlib/libc/ctype/isxdigit.c
@@ -46,5 +46,5 @@ No supporting OS subroutines are required.
 int
 isxdigit (int c)
 {
-	return(__CTYPE_PTR[c+1] & ((_X)|(_N)));
+	return(__CTYPE_PTR[c+1] & ((_ISxdigit)|(_ISdigit)));
 }
diff --git a/newlib/libc/ctype/isxdigit_l.c b/newlib/libc/ctype/isxdigit_l.c
index 726db3190..bbae410c6 100644
--- a/newlib/libc/ctype/isxdigit_l.c
+++ b/newlib/libc/ctype/isxdigit_l.c
@@ -6,6 +6,6 @@
 int
 isxdigit_l (int c, struct __locale_t *locale)
 {
-  return __locale_ctype_ptr_l (locale)[c+1] & ((_X)|(_N));
+  return __locale_ctype_ptr_l (locale)[c+1] & ((_ISxdigit)|(_ISdigit));
 }
 
diff --git a/newlib/libc/include/ctype.h b/newlib/libc/include/ctype.h
index 932a567e2..366b35dc9 100644
--- a/newlib/libc/include/ctype.h
+++ b/newlib/libc/include/ctype.h
@@ -57,14 +57,17 @@ extern int isascii_l (int __c, locale_t __l);
 extern int toascii_l (int __c, locale_t __l);
 #endif
 
-#define	_U	01
-#define	_L	02
-#define	_N	04
-#define	_S	010
-#define _P	020
-#define _C	040
-#define _X	0100
-#define	_B	0200
+enum
+{
+  _ISupper = 01,
+  _ISlower = 02,
+  _ISdigit = 04,
+  _ISspace = 010,
+  _ISpunct = 020,
+  _IScntrl = 040,
+  _ISxdigit = 0100,
+  _ISblank = 0200,
+};
 
 /* For C++ backward-compatibility only.  */
 extern	__IMPORT const char	_ctype_[];
@@ -89,22 +92,22 @@ const char *__locale_ctype_ptr (void);
    an out-of-bounds reference on a 64-bit machine.  */
 #define __ctype_lookup(__c) ((__CTYPE_PTR+sizeof(""[__c]))[(int)(__c)])
 
-#define	isalpha(__c)	(__ctype_lookup(__c)&(_U|_L))
-#define	isupper(__c)	((__ctype_lookup(__c)&(_U|_L))==_U)
-#define	islower(__c)	((__ctype_lookup(__c)&(_U|_L))==_L)
-#define	isdigit(__c)	(__ctype_lookup(__c)&_N)
-#define	isxdigit(__c)	(__ctype_lookup(__c)&(_X|_N))
-#define	isspace(__c)	(__ctype_lookup(__c)&_S)
-#define ispunct(__c)	(__ctype_lookup(__c)&_P)
-#define isalnum(__c)	(__ctype_lookup(__c)&(_U|_L|_N))
-#define isprint(__c)	(__ctype_lookup(__c)&(_P|_U|_L|_N|_B))
-#define	isgraph(__c)	(__ctype_lookup(__c)&(_P|_U|_L|_N))
-#define iscntrl(__c)	(__ctype_lookup(__c)&_C)
+#define	isalpha(__c)	(__ctype_lookup(__c) & (_ISupper|_ISlower))
+#define	isupper(__c)	((__ctype_lookup(__c) & (_ISupper|_ISlower)) == _ISupper)
+#define	islower(__c)	((__ctype_lookup(__c) & (_ISupper|_ISlower)) == _ISlower)
+#define	isdigit(__c)	(__ctype_lookup(__c) & _ISdigit)
+#define	isxdigit(__c)	(__ctype_lookup(__c) & (_ISxdigit|_ISdigit))
+#define	isspace(__c)	(__ctype_lookup(__c) & _ISspace)
+#define ispunct(__c)	(__ctype_lookup(__c) & _ISpunct)
+#define isalnum(__c)	(__ctype_lookup(__c) & (_ISupper|_ISlower|_ISdigit))
+#define isprint(__c)	(__ctype_lookup(__c) & (_ISpunct|_ISupper|_ISlower|_ISdigit|_ISblank))
+#define	isgraph(__c)	(__ctype_lookup(__c) & (_ISpunct|_ISupper|_ISlower|_ISdigit))
+#define iscntrl(__c)	(__ctype_lookup(__c) & _IScntrl)
 
 #if defined(__GNUC__) && __ISO_C_VISIBLE >= 1999
 #define isblank(__c) \
   __extension__ ({ __typeof__ (__c) __x = (__c);		\
-        (__ctype_lookup(__x)&_B) || (int) (__x) == '\t';})
+        (__ctype_lookup(__x)&_ISblank) || (int) (__x) == '\t';})
 #endif
 
 #if __POSIX_VISIBLE >= 200809
@@ -120,22 +123,22 @@ __locale_ctype_ptr_l(locale_t _l)
 #endif
 #define __ctype_lookup_l(__c,__l) ((__locale_ctype_ptr_l(__l)+sizeof(""[__c]))[(int)(__c)])
 
-#define	isalpha_l(__c,__l)	(__ctype_lookup_l(__c,__l)&(_U|_L))
-#define	isupper_l(__c,__l)	((__ctype_lookup_l(__c,__l)&(_U|_L))==_U)
-#define	islower_l(__c,__l)	((__ctype_lookup_l(__c,__l)&(_U|_L))==_L)
-#define	isdigit_l(__c,__l)	(__ctype_lookup_l(__c,__l)&_N)
-#define	isxdigit_l(__c,__l)	(__ctype_lookup_l(__c,__l)&(_X|_N))
-#define	isspace_l(__c,__l)	(__ctype_lookup_l(__c,__l)&_S)
-#define ispunct_l(__c,__l)	(__ctype_lookup_l(__c,__l)&_P)
-#define isalnum_l(__c,__l)	(__ctype_lookup_l(__c,__l)&(_U|_L|_N))
-#define isprint_l(__c,__l)	(__ctype_lookup_l(__c,__l)&(_P|_U|_L|_N|_B))
-#define	isgraph_l(__c,__l)	(__ctype_lookup_l(__c,__l)&(_P|_U|_L|_N))
-#define iscntrl_l(__c,__l)	(__ctype_lookup_l(__c,__l)&_C)
+#define	isalpha_l(__c,__l)	(__ctype_lookup_l(__c,__l) & (_ISupper|_ISlower))
+#define	isupper_l(__c,__l)	((__ctype_lookup_l(__c,__l) & (_ISupper|_ISlower)) == _ISupper)
+#define	islower_l(__c,__l)	((__ctype_lookup_l(__c,__l) & (_ISupper|_ISlower)) == _ISlower)
+#define	isdigit_l(__c,__l)	(__ctype_lookup_l(__c,__l) & _ISdigit)
+#define	isxdigit_l(__c,__l)	(__ctype_lookup_l(__c,__l) & (_ISxdigit|_ISdigit))
+#define	isspace_l(__c,__l)	(__ctype_lookup_l(__c,__l) & _ISspace)
+#define ispunct_l(__c,__l)	(__ctype_lookup_l(__c,__l) & _ISpunct)
+#define isalnum_l(__c,__l)	(__ctype_lookup_l(__c,__l) & (_ISupper|_ISlower|_ISdigit))
+#define isprint_l(__c,__l)	(__ctype_lookup_l(__c,__l) & (_ISpunct|_ISupper|_ISlower|_ISdigit|_ISblank))
+#define	isgraph_l(__c,__l)	(__ctype_lookup_l(__c,__l) & (_ISpunct|_ISupper|_ISlower|_ISdigit))
+#define iscntrl_l(__c,__l)	(__ctype_lookup_l(__c,__l) & _IScntrl)
 
 #if defined(__GNUC__)
 #define isblank_l(__c, __l) \
   __extension__ ({ __typeof__ (__c) __x = (__c);		\
-        (__ctype_lookup_l(__x,__l)&_B) || (int) (__x) == '\t';})
+        (__ctype_lookup_l(__x,__l)&_ISblank) || (int) (__x) == '\t';})
 #endif
 
 #endif /* __POSIX_VISIBLE >= 200809 */