diff --git a/index-pack.c b/index-pack.c
index 042aea884..8331d99a6 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -90,7 +90,7 @@ static SHA_CTX input_ctx;
 static int input_fd, output_fd, mmap_fd;
 
 /* Discard current buffer used content. */
-static void flush()
+static void flush(void)
 {
 	if (input_offset) {
 		if (output_fd >= 0)
diff --git a/read-cache.c b/read-cache.c
index 97c38670b..0f5fb5bc3 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -844,7 +844,7 @@ int read_cache_from(const char *path)
 	die("index file corrupt");
 }
 
-int discard_cache()
+int discard_cache(void)
 {
 	int ret;