diff -r 1003c014bf92 -r 7be10b57f658 src/array_list.c
--- a/src/array_list.c	Thu May 22 16:03:20 2025 +0200
+++ b/src/array_list.c	Thu May 22 16:23:55 2025 +0200
@@ -36,12 +36,13 @@
 
 static void *cx_array_default_realloc(
         void *array,
-        size_t capacity,
+        cx_attr_unused size_t old_capacity,
+        size_t new_capacity,
         size_t elem_size,
         cx_attr_unused CxArrayReallocator *alloc
 ) {
     size_t n;
-    if (cx_szmul(capacity, elem_size, &n)) {
+    if (cx_szmul(new_capacity, elem_size, &n)) {
         errno = EOVERFLOW;
         return NULL;
     }
@@ -58,13 +59,14 @@
 
 static void *cx_array_advanced_realloc(
         void *array,
-        size_t capacity,
+        size_t old_capacity,
+        size_t new_capacity,
         size_t elem_size,
         cx_attr_unused CxArrayReallocator *alloc
 ) {
     // check for overflow
     size_t n;
-    if (cx_szmul(capacity, elem_size, &n)) {
+    if (cx_szmul(new_capacity, elem_size, &n)) {
         errno = EOVERFLOW;
         return NULL;
     }
@@ -77,7 +79,7 @@
     if (array == alloc->ptr2) {
         newmem = cxMalloc(al, n);
         if (newmem != NULL && array != NULL) {
-            memcpy(newmem, array, n);
+            memcpy(newmem, array, old_capacity*elem_size);
         }
     } else {
         newmem = cxRealloc(al, array, n);
@@ -180,7 +182,7 @@
 
         // perform reallocation
         void *newmem = reallocator->realloc(
-                *array, newcap, elem_size, reallocator
+                *array, oldcap, newcap, elem_size, reallocator
         );
         if (newmem == NULL) {
             return 1; // LCOV_EXCL_LINE
@@ -286,7 +288,7 @@
 
         // perform reallocation
         void *newmem = reallocator->realloc(
-                *target, newcap, elem_size, reallocator
+                *target, oldcap, newcap, elem_size, reallocator
         );
         if (newmem == NULL) {
             return 1;
@@ -366,13 +368,14 @@
 
     // store some counts
     size_t old_size = *size;
+    size_t old_capacity = *capacity;
     size_t needed_capacity = old_size + elem_count;
 
     // if we need more than we have, try a reallocation
-    if (needed_capacity > *capacity) {
+    if (needed_capacity > old_capacity) {
         size_t new_capacity = cx_array_align_capacity(needed_capacity, 16, SIZE_MAX);
         void *new_mem = reallocator->realloc(
-                *target, new_capacity, elem_size, reallocator
+                *target, old_capacity, new_capacity, elem_size, reallocator
         );
         if (new_mem == NULL) {
             // give it up right away, there is no contract