diff -r b2ba79f4cb62 -r 8afaeb395b3c src/cx/map.h
--- a/src/cx/map.h	Mon Aug 18 23:00:55 2025 +0200
+++ b/src/cx/map.h	Mon Aug 18 23:06:27 2025 +0200
@@ -280,12 +280,12 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored values
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 static inline CxMapIterator cxMapIteratorValues(const CxMap *map) {
+    if (map == NULL) map = cxEmptyMap;
     return map->cl->iterator(map, CX_MAP_ITERATOR_VALUES);
 }
 
@@ -298,12 +298,12 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored keys
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 static inline CxMapIterator cxMapIteratorKeys(const CxMap *map) {
+    if (map == NULL) map = cxEmptyMap;
     return map->cl->iterator(map, CX_MAP_ITERATOR_KEYS);
 }
 
@@ -316,14 +316,14 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored entries
  * @see cxMapIteratorKeys()
  * @see cxMapIteratorValues()
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 static inline CxMapIterator cxMapIterator(const CxMap *map) {
+    if (map == NULL) map = cxEmptyMap;
     return map->cl->iterator(map, CX_MAP_ITERATOR_PAIRS);
 }
 
@@ -338,10 +338,9 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored values
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 cx_attr_export
 CxMapIterator cxMapMutIteratorValues(CxMap *map);
@@ -355,10 +354,9 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored keys
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 cx_attr_export
 CxMapIterator cxMapMutIteratorKeys(CxMap *map);
@@ -372,12 +370,11 @@
  * @note An iterator iterates over all elements successively. Therefore, the order
  * highly depends on the map implementation and may change arbitrarily when the contents change.
  *
- * @param map the map to create the iterator for
+ * @param map the map to create the iterator for (can be @c NULL)
  * @return an iterator for the currently stored entries
  * @see cxMapMutIteratorKeys()
  * @see cxMapMutIteratorValues()
  */
-cx_attr_nonnull
 cx_attr_nodiscard
 cx_attr_export
 CxMapIterator cxMapMutIterator(CxMap *map);