diff --git a/tests/SpecTests/DocumentsMatchConstraint.php b/tests/SpecTests/DocumentsMatchConstraint.php
index 03f905bd3..e8d4d0de0 100644
--- a/tests/SpecTests/DocumentsMatchConstraint.php
+++ b/tests/SpecTests/DocumentsMatchConstraint.php
@@ -97,6 +97,8 @@ public function evaluate($other, string $description = '', bool $returnResult =
         if (! $success) {
             $this->fail($other, $description, $this->lastFailure);
         }
+
+        return null;
     }
 
     /** @param string|BSONArray[] $expectedType */
diff --git a/tests/UnifiedSpecTests/Constraint/Matches.php b/tests/UnifiedSpecTests/Constraint/Matches.php
index eb963aca9..4346b6dc8 100644
--- a/tests/UnifiedSpecTests/Constraint/Matches.php
+++ b/tests/UnifiedSpecTests/Constraint/Matches.php
@@ -101,6 +101,8 @@ public function evaluate($other, $description = '', $returnResult = false): ?boo
         if (! $success) {
             $this->fail($other, $description, $this->lastFailure);
         }
+
+        return null;
     }
 
     private function assertEquals($expected, $actual, string $keyPath): void