diff --git a/lib/zlib/crc32.c b/lib/zlib/crc32.c
index f8357b0..21a69a8 100644
--- a/lib/zlib/crc32.c
+++ b/lib/zlib/crc32.c
@@ -279,7 +279,7 @@
   combinations of CRC register values and incoming bytes.
  */
 
-local void make_crc_table()
+local void make_crc_table(void)
 {
     unsigned i, j, n;
     z_crc_t p;
@@ -498,7 +498,7 @@
 }
 
 /* Actually do the deed. */
-int main()
+int main(void)
 {
     make_crc_table();
     return 0;
diff --git a/lib/zlib/inflate.c b/lib/zlib/inflate.c
index 8acbef4..aa25e61 100644
--- a/lib/zlib/inflate.c
+++ b/lib/zlib/inflate.c
@@ -342,7 +342,7 @@
 
     a.out > inffixed.h
  */
-void makefixed()
+void makefixed(void)
 {
     unsigned low, size;
     struct inflate_state state;