diff --git a/library/camellia.c b/library/camellia.c
index 5e86e0a..7c499cd 100644
--- a/library/camellia.c
+++ b/library/camellia.c
@@ -278,7 +278,7 @@
     }                                                       \
 }
 
-static void camellia_feistel(uint32_t x[2], uint32_t k[2], uint32_t z[2])
+static void camellia_feistel(const uint32_t x[2], const uint32_t k[2], uint32_t z[2])
 {
     uint32_t I0, I1;
     I0 = x[0] ^ k[0];
@@ -305,7 +305,7 @@
 /*
  * Camellia key schedule (encryption)
  */
-int camellia_setkey_enc( camellia_context *ctx, unsigned char *key, int keysize )
+int camellia_setkey_enc( camellia_context *ctx, const unsigned char *key, int keysize )
 {
     int i, idx;
     uint32_t *RK;
@@ -408,7 +408,7 @@
 /*
  * Camellia key schedule (decryption)
  */
-int camellia_setkey_dec( camellia_context *ctx, unsigned char *key, int keysize )
+int camellia_setkey_dec( camellia_context *ctx, const unsigned char *key, int keysize )
 {
     int i, idx;
     camellia_context cty;
@@ -460,7 +460,7 @@
  */
 void camellia_crypt_ecb( camellia_context *ctx,
                     int mode,
-                    unsigned char input[16],
+                    const unsigned char input[16],
                     unsigned char output[16] )
 {
     int NR;
@@ -522,7 +522,7 @@
                     int mode,
                     int length,
                     unsigned char iv[16],
-                    unsigned char *input,
+                    const unsigned char *input,
                     unsigned char *output )
 {
     int i;
@@ -570,7 +570,7 @@
                        int length,
                        int *iv_off,
                        unsigned char iv[16],
-                       unsigned char *input,
+                       const unsigned char *input,
                        unsigned char *output )
 {
     int c, n = *iv_off;