diff --git a/src/emu/screen.cpp b/src/emu/screen.cpp
index 14ca9d7b947..94c3f796a1d 100644
--- a/src/emu/screen.cpp
+++ b/src/emu/screen.cpp
@@ -1794,7 +1794,8 @@ bool screen_device::update_quads()
 
 void screen_device::update_burnin()
 {
-// TODO: other than being unnecessary (we should use our rand function first off), this is a simplification of how analog signals really works!
+// TODO: other than being unnecessary, this is a simplification of how analog signals really works!
+// It's important not to use machine().rand() here, it can cause machine().rand() used in emulation to desync.
 #undef rand
 	if (!m_burnin.valid())
 		return;