diff --git a/src/Transformation/Adjustment/Opacity.php b/src/Transformation/Adjustment/Opacity.php
index ae057026..ad79b704 100644
--- a/src/Transformation/Adjustment/Opacity.php
+++ b/src/Transformation/Adjustment/Opacity.php
@@ -24,4 +24,5 @@
  */
 class Opacity extends BaseQualifier implements AdjustmentInterface
 {
+    const VALUE_CLASS = OpacityValue::class;
 }
diff --git a/src/Transformation/Adjustment/OpacityValue.php b/src/Transformation/Adjustment/OpacityValue.php
new file mode 100644
index 00000000..a7dadde0
--- /dev/null
+++ b/src/Transformation/Adjustment/OpacityValue.php
@@ -0,0 +1,22 @@
+<?php
+/**
+ * This file is part of the Cloudinary PHP package.
+ *
+ * (c) Cloudinary
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Cloudinary\Transformation;
+
+use Cloudinary\Transformation\NormalizeQualifierMultiValueTrait;
+use Cloudinary\Transformation\QualifierMultiValue;
+
+/**
+ * Class OpacityValue.
+ */
+class OpacityValue extends QualifierMultiValue
+{
+    use NormalizeQualifierMultiValueTrait;
+}
diff --git a/src/Transformation/Qualifier/BaseQualifier.php b/src/Transformation/Qualifier/BaseQualifier.php
index f76a4d8b..13343fe3 100644
--- a/src/Transformation/Qualifier/BaseQualifier.php
+++ b/src/Transformation/Qualifier/BaseQualifier.php
@@ -181,7 +181,7 @@ public function getStringQualifiers()
      */
     public function __toString()
     {
-        $value = ExpressionUtils::normalize((string)$this->value);
+        $value = (string)$this->value;
 
         /** @noinspection TypeUnsafeComparisonInspection */
         return $value == '' ? '' : self::getKey() . static::KEY_VALUE_DELIMITER . $value;
diff --git a/src/Transformation/Qualifier/QualifierValue/NormalizeQualifierMultiValueTrait.php b/src/Transformation/Qualifier/QualifierValue/NormalizeQualifierMultiValueTrait.php
new file mode 100644
index 00000000..9755aeb8
--- /dev/null
+++ b/src/Transformation/Qualifier/QualifierValue/NormalizeQualifierMultiValueTrait.php
@@ -0,0 +1,31 @@
+<?php
+/**
+ * This file is part of the Cloudinary PHP package.
+ *
+ * (c) Cloudinary
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Cloudinary\Transformation;
+
+use Cloudinary\Transformation\Expression\ExpressionUtils;
+
+/**
+ * Trait NormalizeQualifierMultiValueTrait
+ */
+trait NormalizeQualifierMultiValueTrait
+{
+    /**
+     * Normalizes a given string.
+     *
+     * @param $value
+     *
+     * @return string
+     */
+    protected function normalize($value)
+    {
+        return ExpressionUtils::normalize($value);
+    }
+}
diff --git a/src/Transformation/Qualifier/QualifierValue/QualifierMultiValue.php b/src/Transformation/Qualifier/QualifierValue/QualifierMultiValue.php
index 7e6f7888..1cb5b0c2 100644
--- a/src/Transformation/Qualifier/QualifierValue/QualifierMultiValue.php
+++ b/src/Transformation/Qualifier/QualifierValue/QualifierMultiValue.php
@@ -271,7 +271,21 @@ public function __toString()
             static::KEY_VALUE_DELIMITER
         );
 
-        return ArrayUtils::implodeFiltered(static::VALUE_DELIMITER, [$values, $namedValues]);
+        return $this->normalize(ArrayUtils::implodeFiltered(static::VALUE_DELIMITER, [$values, $namedValues]));
+    }
+
+    /**
+     * Normalizes a given value.
+     *
+     * Empty implementation, can be overridden in child classes.
+     *
+     * @param $value
+     *
+     * @return string
+     */
+    protected function normalize($value)
+    {
+        return $value;
     }
 
     /**
diff --git a/tests/Unit/Transformation/TransformationTest.php b/tests/Unit/Transformation/TransformationTest.php
index 0b208f72..b33a12da 100644
--- a/tests/Unit/Transformation/TransformationTest.php
+++ b/tests/Unit/Transformation/TransformationTest.php
@@ -42,6 +42,7 @@
 use Cloudinary\Transformation\Position;
 use Cloudinary\Transformation\PsdTools;
 use Cloudinary\Transformation\Qualifier;
+use Cloudinary\Transformation\QualifiersAction;
 use Cloudinary\Transformation\Quality;
 use Cloudinary\Transformation\Resize;
 use Cloudinary\Transformation\Rotate;
@@ -58,6 +59,23 @@
  */
 final class TransformationTest extends UnitTestCase
 {
+    const SOURCE_VALUE          = "width * 2";
+    const NORMALIZED_VALUE      = "w_mul_2";
+    const NORMALIZED_PARAMETERS = [
+        'angle',
+        'aspect_ratio',
+        'dpr',
+        'effect',
+        'height',
+        'opacity',
+        'quality',
+        'radius',
+        'width',
+        'x',
+        'y',
+        'zoom',
+    ];
+
     public function testTransformation()
     {
         $t = new Transformation();
@@ -625,4 +643,77 @@ public function testUserVariableNamesContainingPredefinedNamesAreNotAffected()
             (string)$transformation
         );
     }
+
+    /**
+     * Data provider of `testNormalizationPredefinedParameters()` method.
+     *
+     * @return array[]
+     */
+    public function normalizationParametersDataProvider()
+    {
+        return array_map(
+            static function ($value) {
+                return ['param' => $value];
+            },
+            self::NORMALIZED_PARAMETERS
+        );
+    }
+
+    /**
+     * Data provider of `testNonNormalizationPredefinedParameters()` method.
+     *
+     * @return array[]
+     */
+    public function nonNormalizationParametersDataProvider()
+    {
+        return array_map(
+            static function ($value) {
+                return ['param' => $value];
+            },
+            array_diff(
+                array_merge(
+                    array_keys(QualifiersAction::SIMPLE_QUALIFIERS),
+                    [
+                        'video_codec',
+                        'overlay',
+                        'underlay',
+                    ]
+                ),
+                array_merge(
+                    self::NORMALIZED_PARAMETERS,
+                    ['if']
+                )
+            )
+        );
+    }
+
+    /**
+     * Tests verify that normalize predefined parameters.
+     *
+     * @dataProvider normalizationParametersDataProvider
+     *
+     * @param $param
+     */
+    public function testNormalizationPredefinedParameters($param)
+    {
+        $transformation = (string)new Transformation([$param => self::SOURCE_VALUE, 'crop' => 'scale']);
+
+        self::assertContains(self::NORMALIZED_VALUE, $transformation, 'should normalize value of #' . $param);
+        self::assertNotContains(self::SOURCE_VALUE, $transformation, 'should normalize value of #' . $param);
+    }
+
+    /**
+     * Tests verify that doesn't normalize predefined parameters.
+     *
+     * @dataProvider nonNormalizationParametersDataProvider
+     *
+     * @param $param
+     */
+    public function testNonNormalizationPredefinedParameters($param)
+    {
+        $transformation = (string)new Transformation([$param => self::SOURCE_VALUE]);
+        self::assertContains(self::SOURCE_VALUE, $transformation, 'should not normalize value of #' . $param);
+        self::assertNotContains(self::NORMALIZED_VALUE, $transformation, 'should not normalize value of #' . $param);
+    }
+
 }