diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa09a5a..7ab883c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## NOT RELEASED
 
+### Changed
+
+- Enable compiler optimization for the `sprintf` function.
+
 ## 1.8.1
 
 ### Changed
diff --git a/src/Input/SendEmailRequest.php b/src/Input/SendEmailRequest.php
index d6d8f87..a786da3 100644
--- a/src/Input/SendEmailRequest.php
+++ b/src/Input/SendEmailRequest.php
@@ -356,7 +356,7 @@ private function requestBody(): array
             $payload['FeedbackForwardingEmailAddressIdentityArn'] = $v;
         }
         if (null === $v = $this->content) {
-            throw new InvalidArgument(sprintf('Missing parameter "Content" for "%s". The value cannot be null.', __CLASS__));
+            throw new InvalidArgument(\sprintf('Missing parameter "Content" for "%s". The value cannot be null.', __CLASS__));
         }
         $payload['Content'] = $v->requestBody();
         if (null !== $v = $this->emailTags) {