diff --git a/contrib/sdk/sources/zlib/Tupfile.lua b/contrib/sdk/sources/zlib/Tupfile.lua
index 3249c45b4c..a1a139fd4f 100755
--- a/contrib/sdk/sources/zlib/Tupfile.lua
+++ b/contrib/sdk/sources/zlib/Tupfile.lua
@@ -10,8 +10,7 @@ CFLAGS = CFLAGS .. " -DHAVE_UNISTD_H -U_Win32 -U_WIN32 -U__MINGW32__"
 compile_gcc{"adler32.c", "compress.c", "crc32.c", "deflate.c", "gzclose.c", "gzlib.c", "gzread.c", "gzwrite.c", "infback.c", "inffast.c", "inflate.c", "inftrees.c", "trees.c", "uncompr.c", "zutil.c"}
 --tup.rule(OBJS, "kos32-ar rcs %o %f", {"../../lib/libz.a", "../../lib/<libz>"})
 
-table.insert(LIBDEPS, "../../lib/<libc.dll.a>")
-table.insert(LIBDEPS, "../../lib/<libdll.a>")
+OBJS.extra_inputs = {"../../lib/<libc.dll.a>", "../../lib/<libdll.a>"}
 
 tup.rule(OBJS, "kos32-ld zlib.def" .. LDFLAGS ..  "-o %o %f -lgcc -lc.dll -ldll " .. tup.getconfig("KPACK_CMD"),
   {"../../bin/libz.dll", extra_outputs = {"../../lib/libz.dll.a", "../../lib/<libz.dll.a>"}})