Index: src/OFMutableString_UTF8.m
==================================================================
--- src/OFMutableString_UTF8.m
+++ src/OFMutableString_UTF8.m
@@ -205,11 +205,11 @@
 
 	if (_s->isUTF8)
 		idx = of_string_utf8_get_position(_s->cString, idx,
 		    _s->cStringLength);
 
-	if (idx > _s->cStringLength)
+	if (idx >= _s->cStringLength)
 		@throw [OFOutOfRangeException exception];
 
 	/* Shortcut if old and new character both are ASCII */
 	if (character < 0x80 && !(_s->cString[idx] & 0x80)) {
 		_s->hashed = false;

Index: src/OFString.m
==================================================================
--- src/OFString.m
+++ src/OFString.m
@@ -263,11 +263,11 @@
 }
 
 ssize_t
 of_string_utf8_decode(const char *buffer_, size_t length, of_unichar_t *ret)
 {
-	const uint8_t *buffer = (const uint8_t *)buffer_;
+	const unsigned char *buffer = (const unsigned char *)buffer_;
 
 	if (!(*buffer & 0x80)) {
 		*ret = buffer[0];
 		return 1;
 	}

Index: src/OFString_UTF8.m
==================================================================
--- src/OFString_UTF8.m
+++ src/OFString_UTF8.m
@@ -165,11 +165,11 @@
 of_string_utf8_get_position(const char *string, size_t idx, size_t length)
 {
 	for (size_t i = 0; i <= idx; i++)
 		if OF_UNLIKELY ((string[i] & 0xC0) == 0x80)
 			if (++idx > length)
-				return OF_NOT_FOUND;
+				@throw [OFInvalidFormatException exception];
 
 	return idx;
 }
 
 @implementation OFString_UTF8

Index: src/macros.h
==================================================================
--- src/macros.h
+++ src/macros.h
@@ -91,12 +91,12 @@
 # define OF_CONST_FUNC __attribute__((__const__))
 # define OF_NO_RETURN_FUNC __attribute__((__noreturn__))
 # define OF_WEAK_REF(sym) __attribute__((__weakref__(sym)))
 #else
 # define OF_INLINE inline
-# define OF_LIKELY(cond) cond
-# define OF_UNLIKELY(cond) cond
+# define OF_LIKELY(cond) (cond)
+# define OF_UNLIKELY(cond) (cond)
 # define OF_CONST_FUNC
 # define OF_NO_RETURN_FUNC
 # define OF_WEAK_REF(sym)
 #endif