--- nono/host/diskimage.cpp	2026/04/29 17:05:21	1.1.1.4
+++ nono/host/diskimage.cpp	2026/04/29 17:05:26	1.1.1.5
@@ -89,7 +89,7 @@ DiskImage::Open(bool read_only, bool cow
 		assert(cowname.empty() == false);
 
 		cowname = gMainApp.GetVMDir() + "/." + cowname + ".cow";
-		cowfd = open(cowname.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0644);
+		cowfd = open(cowname.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0600);
 		if (cowfd < 0) {
 			return false;
 		}