diff --git a/src/test/run-pass/issue-29663.rs b/src/test/run-pass/issue-29663.rs
index 9a77be049feeb..cf925662fc3f3 100644
--- a/src/test/run-pass/issue-29663.rs
+++ b/src/test/run-pass/issue-29663.rs
@@ -10,6 +10,8 @@
 
 // write_volatile causes an LLVM assert with composite types
 
+// ignore-emscripten See #41299: probably a bad optimization
+
 #![feature(volatile)]
 use std::ptr::{read_volatile, write_volatile};