Index: src/OFConstantString.m
==================================================================
--- src/OFConstantString.m
+++ src/OFConstantString.m
@@ -628,11 +628,11 @@
 		[self finishInitialization];
 
 	return [super doubleValue];
 }
 
-- (of_unichar_t*)unicodeString
+- (const of_unichar_t*)unicodeString
 {
 	if (initialized != SIZE_MAX)
 		[self finishInitialization];
 
 	return [super unicodeString];

Index: src/OFString.h
==================================================================
--- src/OFString.h
+++ src/OFString.h
@@ -793,11 +793,11 @@
  * use the result outside the scope of the current autorelease pool, you have to
  * copy it.
  *
  * \return The string as an array of Unicode characters
  */
-- (of_unichar_t*)unicodeString;
+- (const of_unichar_t*)unicodeString;
 
 /**
  * \brief Writes the string into the specified file using UTF-8 encoding.
  *
  * \param path The path of the file to write to

Index: src/OFString.m
==================================================================
--- src/OFString.m
+++ src/OFString.m
@@ -1869,11 +1869,11 @@
 				    exceptionWithClass: isa];
 
 	return value;
 }
 
-- (of_unichar_t*)unicodeString
+- (const of_unichar_t*)unicodeString
 {
 	OFObject *object = [[[OFObject alloc] init] autorelease];
 	of_unichar_t *ret;
 	size_t i, j;