Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -443,11 +443,11 @@
 		AC_SUBST(FOUNDATION_COMPAT_M, "foundation-compat.m")
 	])
 ])
 
 AS_IF([test x"$GOBJC" = x"yes"], [
-	OBJCFLAGS="$OBJCFLAGS -Werror"
+	OBJCFLAGS="$OBJCFLAGS -Wwrite-strings -Werror"
 
 	AC_MSG_CHECKING(whether gcc has bug objc/27438)
 	AC_TRY_COMPILE([
 		#import <objc/objc.h>
 

Index: src/OFHTTPRequest.m
==================================================================
--- src/OFHTTPRequest.m
+++ src/OFHTTPRequest.m
@@ -125,11 +125,11 @@
 		OFMutableDictionary *s_headers;
 		OFDataArray *data;
 		OFEnumerator *enumerator;
 		OFString *key;
 		int status;
-		char *t;
+		const char *t;
 
 		if (requestType == OF_HTTP_REQUEST_TYPE_GET)
 			t = "GET";
 		if (requestType == OF_HTTP_REQUEST_TYPE_HEAD)
 			t = "HEAD";

Index: src/OFString+XMLEscaping.m
==================================================================
--- src/OFString+XMLEscaping.m
+++ src/OFString+XMLEscaping.m
@@ -26,11 +26,12 @@
 int _OFString_XMLEscaping_reference;
 
 @implementation OFString (XMLEscaping)
 - (OFString*)stringByXMLEscaping
 {
-	char *str_c, *append, *tmp;
+	char *str_c, *tmp;
+	const char *append;
 	size_t len, append_len;
 	size_t i, j;
 	OFString *ret;
 
 	j = 0;