diff --git a/src/org/joni/ApplyCaseFold.java b/src/org/joni/ApplyCaseFold.java
index 7dd84ce1..6a8d1c35 100644
--- a/src/org/joni/ApplyCaseFold.java
+++ b/src/org/joni/ApplyCaseFold.java
@@ -41,7 +41,7 @@ public void apply(int from, int[]to, int length, Object o) {
 
             if (Config.CASE_FOLD_IS_APPLIED_INSIDE_NEGATIVE_CCLASS) {
                 if ((inCC && !cc.isNot()) || (!inCC && cc.isNot())) {
-                    if (enc.minLength() > 1 || to[0] >= BitSet.SINGLE_BYTE_SIZE) {
+                    if (enc.minLength() > 1 || to[0] >= BitSet.SINGLE_BYTE_SIZE || enc.codeToMbcLength(to[0]) > 1) {
                         cc.addCodeRange(env, to[0], to[0]);
                     } else {
                         /* /(?i:[^A-C])/.match("a") ==> fail. */