diff --git a/src/test/permutation.cpp b/src/test/permutation.cpp
index 1592a2f45..aeaa5a235 100644
--- a/src/test/permutation.cpp
+++ b/src/test/permutation.cpp
@@ -4,7 +4,7 @@
 #include "util/util.h"
 #include "util/debug.h"
 
-static void swap(unsigned m1, unsigned m2) noexcept { std::swap(m1, m2); }
+ void swap(unsigned m1, unsigned m2) noexcept { std::swap(m1, m2); }
 
 static void test_constructor() {
     permutation p(5);
@@ -43,6 +43,12 @@ static void test_move_after() {
     SASSERT(p(4) == 4);
 }
 
+void apply_permutation_copy(unsigned sz, unsigned const * src, unsigned const * p, unsigned * target) {
+    for (unsigned i = 0; i < sz; i++) {
+        target[i] = src[p[i]];
+    }
+}
+
 static void test_apply_permutation(unsigned sz, unsigned num_tries, unsigned max = UINT_MAX) {
     unsigned_vector data;
     unsigned_vector p;