diff --git a/per-thread-mutex b/per-thread-mutex
index 4b331c18..5147b911 160000
--- a/per-thread-mutex
+++ b/per-thread-mutex
@@ -1 +1 @@
-Subproject commit 4b331c18e7dc5aa2ba616b0d95ff971fb2e52622
+Subproject commit 5147b91143b463a391e9df2a44ed3b7301576a6c