Index: src/OFApplication.m
==================================================================
--- src/OFApplication.m
+++ src/OFApplication.m
@@ -19,11 +19,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <errno.h>
-#include <locale.h>
 #include <signal.h>
 #include <unistd.h>
 
 #import "OFApplication.h"
 #import "OFString.h"

Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -18,11 +18,10 @@
 
 #include <inttypes.h>
 #include <limits.h>
 #include <time.h>
 #include <math.h>
-#include <float.h>
 
 #include <sys/time.h>
 
 #import "OFDate.h"
 #import "OFString.h"

Index: src/OFHTTPClient.m
==================================================================
--- src/OFHTTPClient.m
+++ src/OFHTTPClient.m
@@ -14,11 +14,10 @@
  * file.
  */
 
 #include "config.h"
 
-#include <ctype.h>
 #include <errno.h>
 #include <string.h>
 
 #import "OFHTTPClient.h"
 #import "OFHTTPRequest.h"

Index: src/OFHTTPServer.m
==================================================================
--- src/OFHTTPServer.m
+++ src/OFHTTPServer.m
@@ -16,11 +16,10 @@
 
 #include "config.h"
 
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 
 #import "OFHTTPServer.h"
 #import "OFDataArray.h"
 #import "OFDate.h"
 #import "OFDictionary.h"

Index: src/OFIntrospection.m
==================================================================
--- src/OFIntrospection.m
+++ src/OFIntrospection.m
@@ -15,11 +15,10 @@
  */
 
 #include "config.h"
 
 #include <string.h>
-#include <ctype.h>
 
 #import "OFIntrospection.h"
 #import "OFString.h"
 #import "OFArray.h"
 

Index: src/OFMutableString.m
==================================================================
--- src/OFMutableString.m
+++ src/OFMutableString.m
@@ -14,11 +14,10 @@
  * file.
  */
 
 #include "config.h"
 
-#include <ctype.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <sys/types.h>

Index: src/OFObject+KeyValueCoding.m
==================================================================
--- src/OFObject+KeyValueCoding.m
+++ src/OFObject+KeyValueCoding.m
@@ -15,11 +15,10 @@
  */
 
 #include "config.h"
 
 #include <stdlib.h>
-#include <ctype.h>
 
 #import "OFObject.h"
 #import "OFObject+KeyValueCoding.h"
 #import "OFString.h"
 #import "OFNumber.h"

Index: src/OFString+URLEncoding.m
==================================================================
--- src/OFString+URLEncoding.m
+++ src/OFString+URLEncoding.m
@@ -16,11 +16,10 @@
 
 #include "config.h"
 
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 
 #import "OFString+URLEncoding.h"
 
 #import "OFInvalidFormatException.h"
 #import "OFOutOfMemoryException.h"

Index: src/OFString.m
==================================================================
--- src/OFString.m
+++ src/OFString.m
@@ -14,11 +14,10 @@
  * file.
  */
 
 #include "config.h"
 
-#include <ctype.h>
 #include <errno.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -1665,12 +1664,12 @@
 				      withString: @"\\\n"];
 
 		if (options & OF_JSON_REPRESENTATION_IDENTIFIER) {
 			const char *cString = [self UTF8String];
 
-			if ((!isalpha((int)cString[0]) && cString[0] != '_' &&
-			    cString[0] != '$') ||
+			if ((!of_ascii_isalpha(cString[0]) &&
+			    cString[0] != '_' && cString[0] != '$') ||
 			    strpbrk(cString, " \n\r\t\b\f\\\"'") != NULL) {
 				[JSON prependString: @"\""];
 				[JSON appendString: @"\""];
 			}
 		} else {

Index: src/OFString_UTF8.m
==================================================================
--- src/OFString_UTF8.m
+++ src/OFString_UTF8.m
@@ -17,11 +17,10 @@
 #include "config.h"
 
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 
 #include <sys/types.h>
 
 #import "OFString_UTF8.h"
 #import "OFString_UTF8+Private.h"

Index: src/OFURL.m
==================================================================
--- src/OFURL.m
+++ src/OFURL.m
@@ -16,11 +16,10 @@
 
 #include "config.h"
 
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 
 #import "OFURL.h"
 #import "OFString.h"
 #import "OFArray.h"
 #import "OFXMLElement.h"

Index: src/runtime/hashtable.m
==================================================================
--- src/runtime/hashtable.m
+++ src/runtime/hashtable.m
@@ -14,13 +14,14 @@
  * file.
  */
 
 #include "config.h"
 
+#include <limits.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <stdint.h>
 #include <string.h>
 
 #import "runtime.h"
 #import "runtime-private.h"