diff --git a/ui/build/sandbox_linux.go b/ui/build/sandbox_linux.go
index f77eebb..85c4a9a 100644
--- a/ui/build/sandbox_linux.go
+++ b/ui/build/sandbox_linux.go
@@ -127,6 +127,9 @@
 		// in soong_ui
 		"-e",
 
+		// Mount /proc read-write, necessary to run a nested nsjail or minijail0
+		"--proc_rw",
+
 		// Use a consistent user & group.
 		// Note that these are mapped back to the real UID/GID when
 		// doing filesystem operations, so they're rather arbitrary.