diff --git a/src/base.cc b/src/base.cc
index 53c3e4f..b9adecf 100644
--- a/src/base.cc
+++ b/src/base.cc
@@ -62,13 +62,58 @@ namespace php_arma
     template <typename T, typename T1>
     PHP_ARMA_METHOD(base, replace, T, T1)
     {
-        
+        zval *old_value;
+        zval *new_value;
+        ZEND_PARSE_PARAMETERS_START(2, 2)
+            Z_PARAM_ZVAL(old_value)
+            Z_PARAM_ZVAL(new_value)
+        ZEND_PARSE_PARAMETERS_END();
+
+        if (UNEXPECTED(!zval_check_scalar<T>(old_value) || !zval_check_scalar<T>(new_value) )) {
+            return;
+        }
+
+        auto native = THIS_NATIVE;
+        native->replace(zval_get_scalar<T>(old_value), zval_get_scalar<T>(new_value));
     }
 
     template <typename T, typename T1>
     PHP_ARMA_METHOD(base, transform, T, T1)
     {
-        
+        zend_fcall_info       fci;
+        zend_fcall_info_cache fcc;
+        ZEND_PARSE_PARAMETERS_START(1, 1)
+            Z_PARAM_FUNC(fci, fcc);
+        ZEND_PARSE_PARAMETERS_END();
+
+        zval params[1], retval;
+        fci.param_count = 1;
+        fci.params = params;
+        fci.retval = &retval;
+
+        if constexpr (std::is_same_v<T, cx_double>) {
+            // prevent segfault in `zval_set_scalar()`..
+            ZVAL_UNDEF(&params[0]);
+        }
+
+        auto native = THIS_NATIVE;
+        native->transform([&fci, &fcc](auto&& val) {
+            zval_set_scalar(&fci.params[0], val);
+            zend_call_function(&fci, &fcc);
+            if (!zval_check_scalar<T>(fci.retval)) {
+                zval_ptr_dtor(fci.retval);
+                return T();
+            }
+            T retval = zval_get_scalar<T>(fci.retval);
+            if constexpr (std::is_same_v<T, cx_double>) {
+                zval_ptr_dtor(fci.retval);
+            }
+            return retval;
+        });
+
+        if constexpr (std::is_same_v<T, cx_double>) {
+            zval_ptr_dtor(&params[0]);
+        }
     }
 
     template <typename T, typename T1>
@@ -86,7 +131,7 @@ namespace php_arma
         fci.retval = &retval;
 
         auto native = THIS_NATIVE;
-        native->for_each([&fci, &fcc](T& val) {
+        native->for_each([&fci, &fcc](auto&& val) {
             ZVAL_OBJ(&fci.params[0], mapval_dense<T>::create(&val));
             zend_call_function(&fci, &fcc);
             zval_ptr_dtor(&fci.params[0]);
diff --git a/stubs/internal/Base.php b/stubs/internal/Base.php
index 93eedc9..b716b5c 100644
--- a/stubs/internal/Base.php
+++ b/stubs/internal/Base.php
@@ -82,10 +82,10 @@ interface Base extends Countable
      *
      * Transformation is done column-by-column, and for SpMat only non-zero elements will be transformed.
      *
-     * @param callable $callback (Scalar) => $new_value
+     * @param callable $transform (number|Complex) => $new_value
      * @return void
      */
-    function transform($callback);
+    function transform($transform);
 
     /**
      * For each element, pass its reference to a callback function.
diff --git a/tests/013-foreach.phpt b/tests/013-foreach-transform-replace.phpt
similarity index 63%
rename from tests/013-foreach.phpt
rename to tests/013-foreach-transform-replace.phpt
index f8f66d7..8f6e11a 100644
--- a/tests/013-foreach.phpt
+++ b/tests/013-foreach-transform-replace.phpt
@@ -1,5 +1,5 @@
 --TEST--
-Test for method `forEach()`.
+Test for methods `forEach()`, `transform()`, `replace()`.
 --SKIPIF--
 <?php
 require_once 'includes/loaded.php';
@@ -19,6 +19,13 @@ $mat->forEach(function (Arma\MapVal $elem) {
 });
 echo PHP_EOL;
 $mat->rawPrint();
+$mat->transform(function (int $elem) {
+    return $elem + 4;
+});
+$mat->rawPrint();
+$mat->replace(10, -1);
+$mat->replace(11, -2);
+$mat->rawPrint();
 
 ?>
 --EXPECT--
@@ -27,3 +34,7 @@ $mat->rawPrint();
 1324
 5 6
 7 8
+9 10
+11 12
+9 -1
+-2 12