diff --git a/.psalm/baseline.xml b/.psalm/baseline.xml
index c959447258d..6c8580d8381 100644
--- a/.psalm/baseline.xml
+++ b/.psalm/baseline.xml
@@ -152,10 +152,6 @@
       <code>static::assertThat($haystack, $constraint, $message)</code>
       <code>static::assertThat($haystack, $constraint, $message)</code>
     </MissingThrowsDocblock>
-    <PossiblyInvalidArgument occurrences="2">
-      <code>$expected</code>
-      <code>$expected</code>
-    </PossiblyInvalidArgument>
   </file>
   <file src="src/Framework/Assert/Functions.php">
     <DeprecatedClass occurrences="3">
diff --git a/src/Framework/Constraint/Cardinality/Count.php b/src/Framework/Constraint/Cardinality/Count.php
index 6ff3641b24c..c249c112346 100644
--- a/src/Framework/Constraint/Cardinality/Count.php
+++ b/src/Framework/Constraint/Cardinality/Count.php
@@ -10,10 +10,9 @@
 namespace PHPUnit\Framework\Constraint;
 
 use function count;
-use function is_array;
+use function is_countable;
 use function iterator_count;
 use function sprintf;
-use Countable;
 use EmptyIterator;
 use Generator;
 use Iterator;
@@ -57,7 +56,7 @@ protected function matches($other): bool
      */
     protected function getCountOf($other): ?int
     {
-        if ($other instanceof Countable || is_array($other)) {
+        if (is_countable($other)) {
             return count($other);
         }
 
diff --git a/src/Framework/Constraint/Cardinality/SameSize.php b/src/Framework/Constraint/Cardinality/SameSize.php
index a54679425c0..51e39397a24 100644
--- a/src/Framework/Constraint/Cardinality/SameSize.php
+++ b/src/Framework/Constraint/Cardinality/SameSize.php
@@ -14,7 +14,10 @@
  */
 final class SameSize extends Count
 {
-    public function __construct(iterable $expected)
+    /**
+     * @psalm-param \Countable|iterable $expected
+     */
+    public function __construct($expected)
     {
         parent::__construct((int) $this->getCountOf($expected));
     }