Index: src/OFMutableString.m
==================================================================
--- src/OFMutableString.m
+++ src/OFMutableString.m
@@ -135,10 +135,15 @@
 	size_t len;
 
 	[self freeMemory: string];
 
 	len = strlen(str);
+
+	if (len >= 3 && !memcmp(str, "\xEF\xBB\xBF", 3)) {
+		str += 3;
+		len -= 3;
+	}
 
 	switch (of_string_check_utf8(str, len)) {
 	case 0:
 		isUTF8 = NO;
 		break;
@@ -161,10 +166,15 @@
 - (void)appendCString: (const char*)str
 {
 	size_t strlength;
 
 	strlength = strlen(str);
+
+	if (strlength >= 3 && !memcmp(str, "\xEF\xBB\xBF", 3)) {
+		str += 3;
+		strlength -= 3;
+	}
 
 	switch (of_string_check_utf8(str, strlength)) {
 	case 1:
 		isUTF8 = YES;
 		break;
@@ -179,10 +189,15 @@
 }
 
 - (void)appendCString: (const char*)str
 	   withLength: (size_t)len
 {
+	if (len >= 3 && !memcmp(str, "\xEF\xBB\xBF", 3)) {
+		str += 3;
+		len -= 3;
+	}
+
 	switch (of_string_check_utf8(str, len)) {
 	case 1:
 		isUTF8 = YES;
 		break;
 	case -1:

Index: tests/OFStringTests.m
==================================================================
--- tests/OFStringTests.m
+++ tests/OFStringTests.m
@@ -135,12 +135,12 @@
 					 @"file://testfile.txt"]
 			   encoding: OF_STRING_ENCODING_ISO_8859_1]) &&
 	    [s[1] isEqual: @"testäöü"])
 
 	TEST(@"-[appendCStringWithLength:]",
-	    R([s[0] appendCString: "foobarqux" + 3
-		       withLength: 3]) && [s[0] isEqual: @"foobar"])
+	    R([s[0] appendCString: "foo\xEF\xBB\xBF" "barqux" + 3
+		       withLength: 6]) && [s[0] isEqual: @"foobar"])
 
 	EXPECT_EXCEPTION(@"Detection of invalid UTF-8 encoding #1",
 	    OFInvalidEncodingException,
 	    [OFString stringWithCString: "\xE0\x80"])
 	EXPECT_EXCEPTION(@"Detection of invalid UTF-8 encoding #2",