diff --git a/src/crypto.c b/src/crypto.c
index c5bf6fe1..7d5e42fe 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -860,7 +860,7 @@ bool hkdf_extract(enum l_checksum_type type, const void *key,
 	return (ret == (int) dlen);
 }
 
-bool hkdf_expand(enum l_checksum_type type, const uint8_t *key, size_t key_len,
+bool hkdf_expand(enum l_checksum_type type, const void *key, size_t key_len,
 			const char *info, void *out, size_t out_len)
 {
 	return prf_plus(type, key, key_len, info, out, out_len, 0);
diff --git a/src/crypto.h b/src/crypto.h
index eb48fe5b..b6fa2ec3 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -122,7 +122,7 @@ bool prf_plus(enum l_checksum_type type, const void *key, size_t key_len,
 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,
+bool hkdf_expand(enum l_checksum_type type, const void *key, size_t key_len,
 				const char *info, void *out, size_t out_len);
 
 bool crypto_derive_pairwise_ptk(const uint8_t *pmk, size_t pmk_len,