diff --git a/IxDFCodingStandard/Sniffs/Classes/ForbidMethodDeclarationSniff.php b/IxDFCodingStandard/Sniffs/Classes/ForbidMethodDeclarationSniff.php
index f4de1a9..4038a27 100644
--- a/IxDFCodingStandard/Sniffs/Classes/ForbidMethodDeclarationSniff.php
+++ b/IxDFCodingStandard/Sniffs/Classes/ForbidMethodDeclarationSniff.php
@@ -31,11 +31,8 @@ public function process(File $phpcsFile, $classPointer): void
         $fqcn = ClassHelper::getFullyQualifiedName($phpcsFile, $classPointer);
         foreach ($this->forbiddenMethods as $typeAndMethod => $replacement) {
             [$type, $method] = explode('::', $typeAndMethod);
-            if (! is_subclass_of($fqcn, $type)) {
-                continue;
-            }
 
-            if (! method_exists($fqcn, $method)) {
+            if (! $this->declaresForbiddenMethod($fqcn, $type, $method)) {
                 continue;
             }
 
@@ -46,4 +43,20 @@ public function process(File $phpcsFile, $classPointer): void
             );
         }
     }
+
+    /** @param class-string $fqcn */
+    private function declaresForbiddenMethod(string $fqcn, string $type, string $method): bool
+    {
+        // is_subclass_of()/method_exists() autoload $fqcn. The analysed class may use a deprecated trait
+        // or extend a deprecated class, which emits a deprecation on PHP 8.5+ (e.g. "Trait X used by Y is
+        // deprecated"). That deprecation is a side effect of the analysed code, not of this sniff, and would
+        // otherwise be turned into an exception that aborts the whole file check, so it is silenced here.
+        set_error_handler(static fn(): bool => true, \E_DEPRECATED | \E_USER_DEPRECATED);
+
+        try {
+            return is_subclass_of($fqcn, $type) && method_exists($fqcn, $method);
+        } finally {
+            restore_error_handler();
+        }
+    }
 }
diff --git a/tests/Sniffs/Classes/ForbidMethodDeclarationSniffTest.php b/tests/Sniffs/Classes/ForbidMethodDeclarationSniffTest.php
new file mode 100644
index 0000000..4151e4b
--- /dev/null
+++ b/tests/Sniffs/Classes/ForbidMethodDeclarationSniffTest.php
@@ -0,0 +1,59 @@
+<?php declare(strict_types=1);
+
+namespace IxDFCodingStandard\Sniffs\Classes;
+
+use IxDFCodingStandard\Sniffs\Classes\data\ForbidMethodDeclarationSniff\ForbiddenParent;
+use IxDFCodingStandard\TestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RequiresPhp;
+use PHPUnit\Framework\Attributes\Test;
+
+#[CoversClass(ForbidMethodDeclarationSniff::class)]
+final class ForbidMethodDeclarationSniffTest extends TestCase
+{
+    private const FORBIDDEN_METHODS = [
+        ForbiddenParent::class.'::shouldSend' => '\App\Notifications\Support\ShouldCheckConditionsBeforeSendingOut::shouldBeSent',
+    ];
+
+    #[Test]
+    #[RequiresPhp('>= 8.5.0')]
+    public function it_reports_forbidden_method_even_when_the_class_uses_a_deprecated_trait(): void
+    {
+        // #[\Deprecated] is only allowed on traits since PHP 8.5 (earlier versions reject the fixture at compile time).
+        // Resolving the class autoloads it; using a deprecated trait then emits a deprecation, and the sniff must
+        // silence it instead of letting it abort the whole file check (Internal.Exception).
+        $deprecations = [];
+        set_error_handler(
+            static function (int $errno, string $message) use (&$deprecations): bool {
+                $deprecations[] = $message;
+
+                return true;
+            },
+            \E_DEPRECATED | \E_USER_DEPRECATED
+        );
+
+        try {
+            $report = self::checkFile(
+                __DIR__.'/data/ForbidMethodDeclarationSniff/ChildDeclaringForbiddenMethod.php',
+                ['forbiddenMethods' => self::FORBIDDEN_METHODS]
+            );
+        } finally {
+            restore_error_handler();
+        }
+
+        self::assertSame([], $deprecations, 'The sniff must not leak deprecations triggered while autoloading the analysed class.');
+        self::assertSame(1, $report->getErrorCount());
+        self::assertSniffError($report, 5, ForbidMethodDeclarationSniff::FORBIDDEN_METHOD_DECLARATION);
+    }
+
+    #[Test]
+    public function it_does_not_report_when_the_subclass_does_not_declare_the_forbidden_method(): void
+    {
+        $report = self::checkFile(
+            __DIR__.'/data/ForbidMethodDeclarationSniff/ChildWithoutForbiddenMethod.php',
+            ['forbiddenMethods' => self::FORBIDDEN_METHODS]
+        );
+
+        self::assertNoSniffErrorInFile($report);
+    }
+}
diff --git a/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildDeclaringForbiddenMethod.php b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildDeclaringForbiddenMethod.php
new file mode 100644
index 0000000..c3b44d6
--- /dev/null
+++ b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildDeclaringForbiddenMethod.php
@@ -0,0 +1,13 @@
+<?php declare(strict_types=1);
+
+namespace IxDFCodingStandard\Sniffs\Classes\data\ForbidMethodDeclarationSniff;
+
+final class ChildDeclaringForbiddenMethod extends ForbiddenParent
+{
+    use DeprecatedTrait;
+
+    public function shouldSend(): bool
+    {
+        return true;
+    }
+}
diff --git a/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildWithoutForbiddenMethod.php b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildWithoutForbiddenMethod.php
new file mode 100644
index 0000000..31ecc35
--- /dev/null
+++ b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ChildWithoutForbiddenMethod.php
@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+namespace IxDFCodingStandard\Sniffs\Classes\data\ForbidMethodDeclarationSniff;
+
+final class ChildWithoutForbiddenMethod extends ForbiddenParent
+{
+    public function send(): bool
+    {
+        return true;
+    }
+}
diff --git a/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/DeprecatedTrait.php b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/DeprecatedTrait.php
new file mode 100644
index 0000000..d37f3c1
--- /dev/null
+++ b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/DeprecatedTrait.php
@@ -0,0 +1,8 @@
+<?php declare(strict_types=1);
+
+namespace IxDFCodingStandard\Sniffs\Classes\data\ForbidMethodDeclarationSniff;
+
+#[\Deprecated(message: 'Use composition instead.')]
+trait DeprecatedTrait
+{
+}
diff --git a/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ForbiddenParent.php b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ForbiddenParent.php
new file mode 100644
index 0000000..9234d5a
--- /dev/null
+++ b/tests/Sniffs/Classes/data/ForbidMethodDeclarationSniff/ForbiddenParent.php
@@ -0,0 +1,7 @@
+<?php declare(strict_types=1);
+
+namespace IxDFCodingStandard\Sniffs\Classes\data\ForbidMethodDeclarationSniff;
+
+class ForbiddenParent
+{
+}