1 files changed, 1 insertions, 1 deletions

diff --git a/src/lib/libcrypto/cast/c_skey.c b/src/lib/libcrypto/cast/c_skey.c
index acf2c3eeb5..76e40005c9 100644
--- a/src/lib/libcrypto/cast/c_skey.c
+++ b/src/lib/libcrypto/cast/c_skey.c
@@ -72,7 +72,7 @@
 #define S6 CAST_S_table6
 #define S7 CAST_S_table7
 
-void CAST_set_key(CAST_KEY *key, int len, unsigned char *data)
+void CAST_set_key(CAST_KEY *key, int len, const unsigned char *data)
         {
         CAST_LONG x[16];
         CAST_LONG z[16];