diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index f897e55..16a8ad2 100644
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -28,6 +28,9 @@
 
 #include "udf_sb.h"
 
+#define SURROGATE_MASK 0xfffff800
+#define SURROGATE_PAIR 0x0000d800
+
 static int udf_uni2char_utf8(wchar_t uni,
 			     unsigned char *out,
 			     int boundlen)
@@ -37,6 +40,9 @@ static int udf_uni2char_utf8(wchar_t uni,
 	if (boundlen <= 0)
 		return -ENAMETOOLONG;
 
+	if ((uni & SURROGATE_MASK) == SURROGATE_PAIR)
+		return -EINVAL;
+
 	if (uni < 0x80) {
 		out[u_len++] = (unsigned char)uni;
 	} else if (uni < 0x800) {