diff -r 88fa3381206d -r 7d4e31d295af src/cx/iterator.h
--- a/src/cx/iterator.h	Sat Feb 17 20:22:13 2024 +0100
+++ b/src/cx/iterator.h	Sat Feb 17 20:51:27 2024 +0100
@@ -71,14 +71,6 @@
     void (*next)(void *);
 
     /**
-     * Flag current element for removal, if possible.
-     *
-     * When valid returns false, the behavior of this function is undefined.
-     */
-    __attribute__ ((__nonnull__))
-    bool (*flag_removal)(void *);
-
-    /**
      * Indicates whether this iterator may remove elements.
      */
     bool mutating;
@@ -243,12 +235,11 @@
 #define cxIteratorNext(iter) (iter).base.next(&iter)
 
 /**
- * Flags the current element for removal.
+ * Flags the current element for removal, if this iterator is mutating.
  *
  * @param iter the iterator
- * @return false if this iterator cannot remove the element
  */
-#define cxIteratorFlagRemoval(iter) (iter).base.flag_removal(&iter)
+#define cxIteratorFlagRemoval(iter) (iter).base.remove |= (iter).base.mutating
 
 /**
  * Loops over an iterator.