diff --git a/src/collections_methods.c b/src/collections_methods.c
index 419d7f8..5f26b23 100644
--- a/src/collections_methods.c
+++ b/src/collections_methods.c
@@ -920,7 +920,39 @@ PHP_METHOD(Collection, distinct)
 
 PHP_METHOD(Collection, distinctBy)
 {
-    
+    zend_fcall_info fci;
+    zend_fcall_info_cache fcc;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_FUNC(fci, fcc)
+    ZEND_PARSE_PARAMETERS_END();
+    zend_array* current = COLLECTION_FETCH_CURRENT();
+    compare_func_t cmp = NULL;
+    equal_check_func_t eql = NULL;
+    uint32_t num_elements = zend_hash_num_elements(current);
+    Bucket* ref = (Bucket*)malloc(num_elements * sizeof(Bucket));
+    ARRAY_CLONE(distinct, current);
+    uint32_t idx = 0;
+    INIT_FCI(&fci, 2);
+    ZEND_HASH_FOREACH_BUCKET(distinct, Bucket* bucket)
+        CALLBACK_KEYVAL_INVOKE(params, bucket);
+        if (UNEXPECTED(cmp == NULL))
+        {
+            cmp = compare_func_init(&retval, 0, 0);
+            eql = equal_check_func_init(&retval);
+        }
+        Bucket* dest = &ref[idx++];
+        dest->key = NULL;
+        dest->h = bucket - distinct->arData;
+        memcpy(&dest->val, &retval, sizeof(zval));
+    ZEND_HASH_FOREACH_END();
+    COLLECTIONS_G(cmp) = cmp;
+    array_distinct(distinct, ref, cmp, eql);
+    for (idx = 0; idx < num_elements; ++idx)
+    {
+        zval_ptr_dtor(&ref[idx].val);
+    }
+    free(ref);
+    RETVAL_NEW_COLLECTION(distinct);
 }
 
 PHP_METHOD(Collection, drop)
diff --git a/tests/048-distinct-by.phpt b/tests/048-distinct-by.phpt
new file mode 100644
index 0000000..b7f9caf
--- /dev/null
+++ b/tests/048-distinct-by.phpt
@@ -0,0 +1,22 @@
+--TEST--
+Test Collection::distinctBy().
+--FILE--
+<?php
+$array = [];
+for ($i = 0; $i < 100; ++$i) {
+    $array[] = random_bytes(random_int(1, 10));
+}
+$get_len = function ($value) {
+    return strlen($value);
+};
+$distinct = Collection::init($array)->distinctBy($get_len)->toArray();
+$array1 = [];
+$distinct_idx = array_keys(array_unique(array_map($get_len, $array)));
+foreach ($distinct_idx as $idx) {
+    $array1[] = $array[$idx];
+}
+if ($distinct != $array1) {
+    echo 'Collection::distinct() failed.', PHP_EOL;
+}
+?>
+--EXPECT--