diff -r b53e0e003d7e -r ed710122af44 tests/util_allocator.h
--- a/tests/util_allocator.h	Wed Dec 27 14:54:04 2023 +0100
+++ b/tests/util_allocator.h	Wed Dec 27 16:04:38 2023 +0100
@@ -26,56 +26,77 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef UCX_UTIL_ALLOCATOR_H
-#define UCX_UTIL_ALLOCATOR_H
+#ifndef UCX_TEST_UTIL_ALLOCATOR_H
+#define UCX_TEST_UTIL_ALLOCATOR_H
 
 #include "cx/allocator.h"
 
-#include <set>
+#ifdef __cplusplus
+#extern "C" {
+#endif
 
-struct CxTestingAllocator : public CxAllocator {
+typedef struct CxTestingAllocator {
+    CxAllocator base;
     /**
      * Total number of all allocations (malloc, calloc, realloc).
      * A realloc() does only count when the memory has to be moved.
      */
-    unsigned alloc_total = 0;
+    unsigned alloc_total;
     /**
      * Number of failed allocations (malloc, calloc, realloc).
      */
-    unsigned alloc_failed = 0;
+    unsigned alloc_failed;
     /**
      * Total number of freed pointers.
      * A reallocation also counts as a free when the memory has to be moved.
      */
-    unsigned free_total = 0;
+    unsigned free_total;
     /**
      * Number of failed free invocations.
      * A free() is considered failed, if it has not been performed on tracked memory.
      */
-    unsigned free_failed = 0;
+    unsigned free_failed;
+    /**
+     * The number of currently tracked memory blocks.
+     */
+    size_t tracked_count;
+    /**
+     * The capaciyty of the \c tracked array.
+     */
+    size_t tracked_capacity;
     /**
      * The set of tracked memory blocks.
      */
-    std::set<void *> tracked;
+    void **tracked;
+} CxTestingAllocator;
 
-    /**
-     * Constructs a new testing allocator.
-     */
-    CxTestingAllocator();
 
-    /**
-     * Verifies that this allocator has been used.
-     *
-     * @return true if any allocation was attempted using this allocator
-     */
-    [[nodiscard]] bool used() const;
+/**
+ * Initializes a new testing allocator.
+ */
+void cx_testing_allocator_init(CxTestingAllocator *alloc);
 
-    /**
-     * Verifies that all allocated memory blocks are freed and no free occurred twice.
-     *
-     * @return true iff all tracked allocations / deallocations were valid
-     */
-    [[nodiscard]] bool verify() const;
-};
+/**
+ * Destroys a testing allocator.
+ */
+void cx_testing_allocator_destroy(CxTestingAllocator *alloc);
 
-#endif // UCX_UTIL_ALLOCATOR_H
+/**
+ * Verifies that this allocator has been used.
+ *
+ * @return true if any allocation was attempted using this allocator
+ */
+bool cx_testing_allocator_used(CxTestingAllocator const *alloc);
+
+/**
+ * Verifies that all allocated memory blocks are freed and no free occurred twice.
+ *
+ * @return true iff all tracked allocations / deallocations were valid
+ */
+bool cx_testing_allocator_verify(CxTestingAllocator const *alloc);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // UCX_TEST_UTIL_ALLOCATOR_H