diff --git a/etc/sphinx.conf.in b/etc/sphinx.conf.in
index 260f1a4..b1bb4fa 100644
--- a/etc/sphinx.conf.in
+++ b/etc/sphinx.conf.in
@@ -218,5 +218,6 @@
 	seamless_rotate		= 1
 	preopen_indexes		= 1
 	unlink_old		= 1
+	thread_stack		= 512k
 	workers			= threads # for RT to work
 }