diff --git a/src/base/io.lua b/src/base/io.lua
index 885b6e13..e7981e5a 100644
--- a/src/base/io.lua
+++ b/src/base/io.lua
@@ -11,7 +11,7 @@
 --
 
 	premake.override(io, "open", function(base, fname, mode)
-		if mode and mode:find("w") then
+		if mode and (mode:find("w") or mode:find("a"))  then
 			local dir = path.getdirectory(fname)
 			ok, err = os.mkdir(dir)
 			if not ok then