diff --git a/tools/testing/radix-tree/regression1.c b/tools/testing/radix-tree/regression1.c
index 2d03a63bb79c..0d6813a61b37 100644
--- a/tools/testing/radix-tree/regression1.c
+++ b/tools/testing/radix-tree/regression1.c
@@ -43,7 +43,7 @@
 #include "regression.h"
 
 static RADIX_TREE(mt_tree, GFP_KERNEL);
-static pthread_mutex_t mt_lock;
+static pthread_mutex_t mt_lock = PTHREAD_MUTEX_INITIALIZER;
 
 struct page {
 	pthread_mutex_t lock;