diff --git a/cmac.c b/cmac.c
index e543e06..531ee48 100644
--- a/cmac.c
+++ b/cmac.c
@@ -56,7 +56,7 @@ static void cmac_truncate(uint8_t *dest, uint8_t *tag, uint_fast8_t tag_len) {
     memmove(dest, tag, tag_len);
 }
 
-void cmac_aes128(uint8_t *dest, uint8_t *msg, size_t msg_len,
+void cmac_aes128(void *dest, void *msg, size_t msg_len,
                  uint_fast8_t tag_len) {
     /* Simulate ceiling integer division by adding a block if remainder */
     size_t num_blocks = (msg_len >> 4) + (msg_len & 15 ? 1 : 0);
diff --git a/cmac.h b/cmac.h
index 1bb9ce8..e45cb2d 100644
--- a/cmac.h
+++ b/cmac.h
@@ -5,7 +5,7 @@
 
 #include "block.h"
 
-void cmac_aes128(uint8_t *, uint8_t *, size_t, uint_fast8_t);
-void cmac_aes128_expand_key(uint8_t const *const, uint8_t *, uint8_t *);
+void cmac_aes128(void *, void *, size_t, uint_fast8_t);
+void cmac_aes128_expand_key(uint8_t const *, uint8_t *, uint8_t *);
 void cmac_aes128_init(const uint8_t *);
 void cmac_get_subkeys(uint8_t *);