diff -r 61d5197d612b -r 4523f6d42512 src/compare.c
--- a/src/compare.c	Mon Dec 18 15:13:26 2023 +0100
+++ b/src/compare.c	Mon Dec 18 16:04:21 2023 +0100
@@ -199,3 +199,15 @@
     }
 }
 
+int cx_cmp_ptr(
+        void const *ptr1,
+        void const *ptr2
+) {
+    uintptr_t p1 = (uintptr_t) ptr1;
+    uintptr_t p2 = (uintptr_t) ptr2;
+    if (p1 == p2) {
+        return 0;
+    } else {
+        return p1 < p2 ? -1 : 1;
+    }
+}