diff --git a/include/arraylist.h b/include/arraylist.h
index a22f97e..7f0af97 100644
--- a/include/arraylist.h
+++ b/include/arraylist.h
@@ -22,7 +22,7 @@ typedef enum {
     ARRLIST_INVALID_SLICE,
 } ArrayListErr;
 
-ArrayList *arraylist_init(size_t capacity, size_t elem_size);
+ArrayListErr arraylist_init(ArrayList **arr, size_t capacity, size_t elem_size);
 ArrayListErr arraylist_destroy(ArrayList **arr);
 ArrayListErr arraylist_clear(ArrayList *arr);
 ArrayList *arraylist_clone(const ArrayList *arr);
diff --git a/src/arraylist.c b/src/arraylist.c
index bbbaa65..e38808d 100644
--- a/src/arraylist.c
+++ b/src/arraylist.c
@@ -26,34 +26,40 @@ struct ArraySlice {
 static ArrayListErr arraylist_grow(ArrayList *arr);
 static ArrayListErr arraylist_shrink(ArrayList *arr);
 
-ArrayList *arraylist_init(size_t capacity, size_t elem_size) {
+ArrayListErr arraylist_init(ArrayList **arr, size_t capacity, size_t elem_size) {
+    if (arr == NULL || *arr == NULL) {
+        return ARRLIST_NULL_ARG;
+    }
+
     if (capacity == 0) {
-        return NULL;
+        return ARRLIST_INVALID_CAPACITY;
     }
 
     if (elem_size == 0) {
-        return NULL;
+        return ARRLIST_INVALID_ELEM_SIZE;
     }
 
     if (capacity > SIZE_MAX / elem_size) {
-        return NULL;
+        return ARRLIST_INVALID_CAPACITY;
     }
 
-    ArrayList *arr = malloc(sizeof(ArrayList));
+    ArrayList *new_arr = malloc(sizeof(ArrayList));
     if (arr == NULL) {
-        return NULL;
+        return ARRLIST_BAD_ALLOC;
     }
-    arr->capacity = capacity;
-    arr->elem_size = elem_size;
-    arr->len = 0;
-    arr->borrows = 0;
-    arr->buffer = malloc(capacity * elem_size);
-    if (arr->buffer == NULL) {
+
+    new_arr->capacity = capacity;
+    new_arr->elem_size = elem_size;
+    new_arr->len = 0;
+    new_arr->borrows = 0;
+    new_arr->buffer = malloc(capacity * elem_size);
+    if (new_arr->buffer == NULL) {
         free(arr);
         return NULL;
     }
 
-    return arr;
+    *arr = new_arr;
+    return ARRLIST_OK;
 }
 
 ArrayListErr arraylist_destroy(ArrayList **arr) {