diff --git a/contrib/C_Layer/ASM/Tupfile.lua b/contrib/C_Layer/ASM/Tupfile.lua
index 419f7917a0..880c1d65ac 100644
--- a/contrib/C_Layer/ASM/Tupfile.lua
+++ b/contrib/C_Layer/ASM/Tupfile.lua
@@ -1,2 +1,2 @@
 if tup.getconfig("NO_FASM") ~= "" then return end
-tup.foreach_rule("*.asm", "fasm %f ", "../OBJ/%B.obj")
+tup.foreach_rule("*.asm", "fasm %f %o", "../OBJ/%B.obj")