diff --git a/libs/vr/libpdx/service_tests.cpp b/libs/vr/libpdx/service_tests.cpp
index e623abf..938d737 100644
--- a/libs/vr/libpdx/service_tests.cpp
+++ b/libs/vr/libpdx/service_tests.cpp
@@ -51,22 +51,24 @@
 //             method(IoVecMatcher(IoVecArray{{ptr1, size1}, {ptr2, size2}})));
 using IoVecArray = std::vector<iovec>;
 MATCHER_P(IoVecMatcher, iovec_array, "") {
+  auto local_arg = arg;
   for (const iovec& item : iovec_array) {
-    if (arg->iov_base != item.iov_base || arg->iov_len != item.iov_len)
+    if (local_arg->iov_base != item.iov_base || local_arg->iov_len != item.iov_len)
       return false;
-    arg++;
+    local_arg++;
   }
   return true;
 }
 
 using IoVecData = std::vector<std::string>;
 MATCHER_P(IoVecDataMatcher, iovec_data, "") {
+  auto local_arg = arg;
   for (const std::string& item : iovec_data) {
-    std::string data{reinterpret_cast<const char*>(arg->iov_base),
-                     arg->iov_len};
+    std::string data{reinterpret_cast<const char*>(local_arg->iov_base),
+                     local_arg->iov_len};
     if (data != item)
       return false;
-    arg++;
+    local_arg++;
   }
   return true;
 }