diff --git a/src/crypto.c b/src/crypto.c
index 6c70eb9a..fe91a0b3 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -770,9 +770,9 @@ bool kdf_sha384(const void *key, size_t key_len,
  *
  * Null key equates to a zero key (makes calls in EAP-PWD more convenient)
  */
-bool hkdf_extract(enum l_checksum_type type, const uint8_t *key,
+bool hkdf_extract(enum l_checksum_type type, const void *key,
 				size_t key_len, uint8_t num_args,
-				uint8_t *out, ...)
+				void *out, ...)
 {
 	struct l_checksum *hmac;
 	struct iovec iov[num_args];
diff --git a/src/crypto.h b/src/crypto.h
index 89e2402c..65e6c6ef 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -109,8 +109,8 @@ bool prf_sha1(const void *key, size_t key_len,
 bool prf_plus_sha1(const void *key, size_t key_len,
 		const void *prefix, size_t prefix_len,
 		const void *data, size_t data_len, void *output, size_t size);
-bool hkdf_extract(enum l_checksum_type type, const uint8_t *key, size_t key_len,
-				uint8_t num_args, uint8_t *out, ...);
+bool hkdf_extract(enum l_checksum_type type, const void *key, size_t key_len,
+				uint8_t num_args, void *out, ...);
 
 bool hkdf_expand(enum l_checksum_type type, const uint8_t *key, size_t key_len,
 				const char *info, size_t info_len, void *out,