diff --git a/tests/lib/test_assert.c b/tests/lib/test_assert.c
index 8f1f4f2bad..a4535651d4 100644
--- a/tests/lib/test_assert.c
+++ b/tests/lib/test_assert.c
@@ -27,7 +27,7 @@
 #include <assert.h>
 
 __attribute__((noinline))
-void func_for_bt(int number)
+static void func_for_bt(int number)
 {
 	assert(number > 2);
 	assertf(number > 3, "(A) the number was %d", number);