diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 7337d4422d..a2de39f2ca 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -614,7 +614,7 @@ done:
 
 static struct ref_iterator *reftable_be_iterator_begin(struct ref_store *ref_store,
 						       const char *prefix,
-						       const char **exclude_patterns,
+						       const char **exclude_patterns UNUSED,
 						       unsigned int flags)
 {
 	struct reftable_ref_iterator *main_iter, *worktree_iter;
@@ -1123,9 +1123,9 @@ done:
 	return ret;
 }
 
-static int reftable_be_transaction_abort(struct ref_store *ref_store,
+static int reftable_be_transaction_abort(struct ref_store *ref_store UNUSED,
 					 struct ref_transaction *transaction,
-					 struct strbuf *err)
+					 struct strbuf *err UNUSED)
 {
 	struct reftable_transaction_data *tx_data = transaction->backend_data;
 	free_transaction_data(tx_data);
@@ -1315,7 +1315,7 @@ done:
 	return ret;
 }
 
-static int reftable_be_transaction_finish(struct ref_store *ref_store,
+static int reftable_be_transaction_finish(struct ref_store *ref_store UNUSED,
 					  struct ref_transaction *transaction,
 					  struct strbuf *err)
 {
@@ -1726,8 +1726,8 @@ static int reftable_reflog_iterator_advance(struct ref_iterator *ref_iterator)
 	return ITER_OK;
 }
 
-static int reftable_reflog_iterator_peel(struct ref_iterator *ref_iterator,
-						 struct object_id *peeled)
+static int reftable_reflog_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
+					 struct object_id *peeled UNUSED)
 {
 	BUG("reftable reflog iterator cannot be peeled");
 	return -1;
@@ -1988,7 +1988,7 @@ done:
 
 static int reftable_be_create_reflog(struct ref_store *ref_store,
 				     const char *refname,
-				     struct strbuf *errmsg)
+				     struct strbuf *errmsg UNUSED)
 {
 	struct reftable_ref_store *refs =
 		reftable_be_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
diff --git a/reftable/blocksource.c b/reftable/blocksource.c
index eeed254ba9..abce4bb2e1 100644
--- a/reftable/blocksource.c
+++ b/reftable/blocksource.c
@@ -13,14 +13,14 @@ https://developers.google.com/open-source/licenses/bsd
 #include "reftable-blocksource.h"
 #include "reftable-error.h"
 
-static void strbuf_return_block(void *b, struct reftable_block *dest)
+static void strbuf_return_block(void *b UNUSED, struct reftable_block *dest)
 {
 	if (dest->len)
 		memset(dest->data, 0xff, dest->len);
 	reftable_free(dest->data);
 }
 
-static void strbuf_close(void *b)
+static void strbuf_close(void *b UNUSED)
 {
 }
 
@@ -55,7 +55,7 @@ void block_source_from_strbuf(struct reftable_block_source *bs,
 	bs->arg = buf;
 }
 
-static void malloc_return_block(void *b, struct reftable_block *dest)
+static void malloc_return_block(void *b UNUSED, struct reftable_block *dest)
 {
 	if (dest->len)
 		memset(dest->data, 0xff, dest->len);
@@ -85,7 +85,7 @@ static uint64_t file_size(void *b)
 	return ((struct file_block_source *)b)->size;
 }
 
-static void file_return_block(void *b, struct reftable_block *dest)
+static void file_return_block(void *b UNUSED, struct reftable_block *dest UNUSED)
 {
 }
 
diff --git a/reftable/generic.c b/reftable/generic.c
index 28ae26145e..a00725d9c4 100644
--- a/reftable/generic.c
+++ b/reftable/generic.c
@@ -201,17 +201,19 @@ int iterator_next(struct reftable_iterator *it, struct reftable_record *rec)
 	return it->ops->next(it->iter_arg, rec);
 }
 
-static int empty_iterator_seek(void *arg, struct reftable_record *want)
+static int empty_iterator_seek(void *arg UNUSED,
+			       struct reftable_record *want UNUSED)
 {
 	return 0;
 }
 
-static int empty_iterator_next(void *arg, struct reftable_record *rec)
+static int empty_iterator_next(void *arg UNUSED,
+			       struct reftable_record *rec UNUSED)
 {
 	return 1;
 }
 
-static void empty_iterator_close(void *arg)
+static void empty_iterator_close(void *arg UNUSED)
 {
 }
 
diff --git a/reftable/iter.c b/reftable/iter.c
index fddea31e51..9e8b2952fd 100644
--- a/reftable/iter.c
+++ b/reftable/iter.c
@@ -127,7 +127,8 @@ static int indexed_table_ref_iter_next_block(struct indexed_table_ref_iter *it)
 	return 0;
 }
 
-static int indexed_table_ref_iter_seek(void *p, struct reftable_record *want)
+static int indexed_table_ref_iter_seek(void *p UNUSED,
+				       struct reftable_record *want UNUSED)
 {
 	BUG("seeking indexed table is not supported");
 	return -1;
diff --git a/reftable/record.c b/reftable/record.c
index a2cba5ef74..2ec0c6d346 100644
--- a/reftable/record.c
+++ b/reftable/record.c
@@ -516,7 +516,7 @@ static void reftable_obj_record_release(void *rec)
 	memset(obj, 0, sizeof(struct reftable_obj_record));
 }
 
-static void reftable_obj_record_print(const void *rec, int hash_size)
+static void reftable_obj_record_print(const void *rec, int hash_size UNUSED)
 {
 	const struct reftable_obj_record *obj = rec;
 	char hex[GIT_MAX_HEXSZ + 1] = { 0 };
@@ -532,7 +532,7 @@ static void reftable_obj_record_print(const void *rec, int hash_size)
 }
 
 static void reftable_obj_record_copy_from(void *rec, const void *src_rec,
-					  int hash_size)
+					  int hash_size UNUSED)
 {
 	struct reftable_obj_record *obj = rec;
 	const struct reftable_obj_record *src =
@@ -559,7 +559,7 @@ static uint8_t reftable_obj_record_val_type(const void *rec)
 }
 
 static int reftable_obj_record_encode(const void *rec, struct string_view s,
-				      int hash_size)
+				      int hash_size UNUSED)
 {
 	const struct reftable_obj_record *r = rec;
 	struct string_view start = s;
@@ -594,7 +594,8 @@ static int reftable_obj_record_encode(const void *rec, struct string_view s,
 
 static int reftable_obj_record_decode(void *rec, struct strbuf key,
 				      uint8_t val_type, struct string_view in,
-				      int hash_size, struct strbuf *scratch UNUSED)
+				      int hash_size UNUSED,
+				      struct strbuf *scratch UNUSED)
 {
 	struct string_view start = in;
 	struct reftable_obj_record *r = rec;
@@ -647,12 +648,13 @@ static int reftable_obj_record_decode(void *rec, struct strbuf key,
 	return start.len - in.len;
 }
 
-static int not_a_deletion(const void *p)
+static int not_a_deletion(const void *p UNUSED)
 {
 	return 0;
 }
 
-static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
+static int reftable_obj_record_equal_void(const void *a, const void *b,
+					  int hash_size UNUSED)
 {
 	struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 	struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
@@ -1066,7 +1068,7 @@ static void reftable_index_record_key(const void *r, struct strbuf *dest)
 }
 
 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
-					    int hash_size)
+					    int hash_size UNUSED)
 {
 	struct reftable_index_record *dst = rec;
 	const struct reftable_index_record *src = src_rec;
@@ -1082,13 +1084,13 @@ static void reftable_index_record_release(void *rec)
 	strbuf_release(&idx->last_key);
 }
 
-static uint8_t reftable_index_record_val_type(const void *rec)
+static uint8_t reftable_index_record_val_type(const void *rec UNUSED)
 {
 	return 0;
 }
 
 static int reftable_index_record_encode(const void *rec, struct string_view out,
-					int hash_size)
+					int hash_size UNUSED)
 {
 	const struct reftable_index_record *r =
 		(const struct reftable_index_record *)rec;
@@ -1104,8 +1106,10 @@ static int reftable_index_record_encode(const void *rec, struct string_view out,
 }
 
 static int reftable_index_record_decode(void *rec, struct strbuf key,
-					uint8_t val_type, struct string_view in,
-					int hash_size, struct strbuf *scratch UNUSED)
+					uint8_t val_type UNUSED,
+					struct string_view in,
+					int hash_size UNUSED,
+					struct strbuf *scratch UNUSED)
 {
 	struct string_view start = in;
 	struct reftable_index_record *r = rec;
@@ -1122,7 +1126,8 @@ static int reftable_index_record_decode(void *rec, struct strbuf key,
 	return start.len - in.len;
 }
 
-static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
+static int reftable_index_record_equal(const void *a, const void *b,
+				       int hash_size UNUSED)
 {
 	struct reftable_index_record *ia = (struct reftable_index_record *) a;
 	struct reftable_index_record *ib = (struct reftable_index_record *) b;
@@ -1137,7 +1142,7 @@ static int reftable_index_record_cmp(const void *_a, const void *_b)
 	return strbuf_cmp(&a->last_key, &b->last_key);
 }
 
-static void reftable_index_record_print(const void *rec, int hash_size)
+static void reftable_index_record_print(const void *rec, int hash_size UNUSED)
 {
 	const struct reftable_index_record *idx = rec;
 	/* TODO: escape null chars? */
diff --git a/reftable/stack_test.c b/reftable/stack_test.c
index f84b92f312..1a638cd2e0 100644
--- a/reftable/stack_test.c
+++ b/reftable/stack_test.c
@@ -399,7 +399,7 @@ static void test_reftable_stack_auto_compaction_fails_gracefully(void)
 	clear_dir(dir);
 }
 
-static int write_error(struct reftable_writer *wr, void *arg)
+static int write_error(struct reftable_writer *wr UNUSED, void *arg)
 {
 	return *((int *)arg);
 }
@@ -816,7 +816,7 @@ static void test_reflog_expire(void)
 	reftable_log_record_release(&log);
 }
 
-static int write_nothing(struct reftable_writer *wr, void *arg)
+static int write_nothing(struct reftable_writer *wr, void *arg UNUSED)
 {
 	reftable_writer_set_limits(wr, 1, 1);
 	return 0;
diff --git a/reftable/test_framework.c b/reftable/test_framework.c
index 4066924eee..a07fec5d84 100644
--- a/reftable/test_framework.c
+++ b/reftable/test_framework.c
@@ -21,7 +21,7 @@ ssize_t strbuf_add_void(void *b, const void *data, size_t sz)
 	return sz;
 }
 
-int noop_flush(void *arg)
+int noop_flush(void *arg UNUSED)
 {
 	return 0;
 }
diff --git a/reftable/writer.c b/reftable/writer.c
index 45b3e9ce1f..9d5e6072bc 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -544,7 +544,7 @@ static void write_object_record(void *void_arg, void *key)
 done:;
 }
 
-static void object_record_free(void *void_arg, void *key)
+static void object_record_free(void *void_arg UNUSED, void *key)
 {
 	struct obj_index_tree_node *entry = key;
 
diff --git a/t/unit-tests/t-reftable-merged.c b/t/unit-tests/t-reftable-merged.c
index 2d65d5c3cb..99f8fcadfe 100644
--- a/t/unit-tests/t-reftable-merged.c
+++ b/t/unit-tests/t-reftable-merged.c
@@ -22,7 +22,7 @@ static ssize_t strbuf_add_void(void *b, const void *data, const size_t sz)
 	return sz;
 }
 
-static int noop_flush(void *arg)
+static int noop_flush(void *arg UNUSED)
 {
 	return 0;
 }