diff --git a/src/Assert.php b/src/Assert.php
index c87fbf4..6834e5c 100644
--- a/src/Assert.php
+++ b/src/Assert.php
@@ -571,7 +571,7 @@ public static function isAOf(mixed $value, mixed $class, string $message = ''):
         static::string($class, 'Expected class as a string. Got: %s');
 
         if (!\is_a($value, $class, \is_string($value))) {
-            static::reportInvalidArgument(sprintf(
+            static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected an instance of this class or to this class among its parents "%2$s". Got: %s',
                 static::valueToString($value),
                 $class
@@ -599,7 +599,7 @@ public static function isNotA(mixed $value, mixed $class, string $message = ''):
         static::string($class, 'Expected class as a string. Got: %s');
 
         if (\is_a($value, $class, \is_string($value))) {
-            static::reportInvalidArgument(sprintf(
+            static::reportInvalidArgument(\sprintf(
                 $message ?: 'Expected an instance of this class or to this class among its parents other than "%2$s". Got: %s',
                 static::valueToString($value),
                 $class
@@ -631,7 +631,7 @@ public static function isAnyOf(mixed $value, mixed $classes, string $message = '
             }
         }
 
-        static::reportInvalidArgument(sprintf(
+        static::reportInvalidArgument(\sprintf(
             $message ?: 'Expected an instance of any of this classes or any of those classes among their parents "%2$s". Got: %s',
             static::valueToString($value),
             \implode(', ', \iterator_to_array($classes))