diff --git a/include/bfdev/sha1.h b/include/bfdev/sha1.h
index 1d237915..4c6ff04a 100644
--- a/include/bfdev/sha1.h
+++ b/include/bfdev/sha1.h
@@ -32,7 +32,7 @@ struct bfdev_sha1_ctx {
 };
 
 extern void
-bfdev_sha1_update(bfdev_sha1_ctx_t *ctx, const char *data, size_t size);
+bfdev_sha1_update(bfdev_sha1_ctx_t *ctx, const void *data, size_t size);
 
 extern void
 bfdev_sha1_finish(bfdev_sha1_ctx_t *ctx, void *hash);
diff --git a/include/bfdev/sha2.h b/include/bfdev/sha2.h
index 1cbe7072..b6b8a28f 100644
--- a/include/bfdev/sha2.h
+++ b/include/bfdev/sha2.h
@@ -47,7 +47,7 @@ struct bfdev_sha2_ctx {
 };
 
 extern void
-bfdev_sha2_update(bfdev_sha2_ctx_t *ctx, const char *data, size_t size);
+bfdev_sha2_update(bfdev_sha2_ctx_t *ctx, const void *data, size_t size);
 
 extern void
 bfdev_sha224_finish(bfdev_sha2_ctx_t *ctx, void *hash);
diff --git a/src/crypto/sha1.c b/src/crypto/sha1.c
index 85695a4f..30d4ecac 100644
--- a/src/crypto/sha1.c
+++ b/src/crypto/sha1.c
@@ -21,7 +21,7 @@ sha1_transform_block(bfdev_sha1_ctx_t *ctx, const void *src, size_t blocks)
 }
 
 export void
-bfdev_sha1_update(bfdev_sha1_ctx_t *ctx, const char *data, size_t size)
+bfdev_sha1_update(bfdev_sha1_ctx_t *ctx, const void *data, size_t size)
 {
     bfdev_sha1_base_update(ctx, data, size, sha1_transform_block);
 }
diff --git a/src/crypto/sha2.c b/src/crypto/sha2.c
index 7c3b89b5..95165a16 100644
--- a/src/crypto/sha2.c
+++ b/src/crypto/sha2.c
@@ -21,7 +21,7 @@ sha2_transform_block(bfdev_sha2_ctx_t *ctx, const void *src, size_t blocks)
 }
 
 export void
-bfdev_sha2_update(bfdev_sha2_ctx_t *ctx, const char *data, size_t size)
+bfdev_sha2_update(bfdev_sha2_ctx_t *ctx, const void *data, size_t size)
 {
     bfdev_sha2_base_update(ctx, data, size, sha2_transform_block);
 }