diff --git a/tests/stackusage/stackusage.c b/tests/stackusage/stackusage.c
index 6a86d90..7d08fa7 100644
--- a/tests/stackusage/stackusage.c
+++ b/tests/stackusage/stackusage.c
@@ -15,7 +15,7 @@
  */
 #define MAX_STACK_ENTRIES 1024
 static uint32_t g_stackbuf[MAX_STACK_ENTRIES];
-static uint32_t *g_stackptr;
+static volatile uint32_t *g_stackptr;
 
 void start_stack_measuring()
 {