diff --git a/lib/Doctrine/ORM/Query.php b/lib/Doctrine/ORM/Query.php
index 385b8c8ea..a86cf6201 100644
--- a/lib/Doctrine/ORM/Query.php
+++ b/lib/Doctrine/ORM/Query.php
@@ -371,6 +371,25 @@ final class Query extends AbstractQuery
         $this->_em->getCache()->evictEntityRegion($className);
     }
 
+    private function getAllDiscriminators(ClassMetadata $classMetadata)
+    {
+        // FIXME: this code is copied from SqlWalker->getAllDiscriminators()
+        $hierarchyClasses = $classMetadata->subClasses;
+        $hierarchyClasses[] = $classMetadata->name;
+
+        $discriminators = [];
+        foreach ($hierarchyClasses as $class) {
+            $currentMetadata = $this->getEntityManager()->getClassMetadata($class);
+            $currentDiscriminator = $currentMetadata->discriminatorValue;
+
+            if (null !== $currentDiscriminator) {
+                $discriminators[$currentDiscriminator] = null;
+            }
+        }
+
+        return $discriminators;
+    }
+
     /**
      * Processes query parameter mappings.
      *
@@ -398,6 +417,10 @@ final class Query extends AbstractQuery
                 $value = $value->getMetadataValue($rsm->metadataParameterMapping[$key]);
             }
 
+            if (isset($rsm->discriminatorParameters[$key]) && $value instanceof ClassMetadata) {
+                $value = array_keys($this->getAllDiscriminators($value));
+            }
+
             $value = $this->processParameterValue($value);
             $type  = ($parameter->getValue() === $value)
                 ? $parameter->getType()
diff --git a/lib/Doctrine/ORM/Query/ResultSetMapping.php b/lib/Doctrine/ORM/Query/ResultSetMapping.php
index 5c4550980..058ae8d4c 100644
--- a/lib/Doctrine/ORM/Query/ResultSetMapping.php
+++ b/lib/Doctrine/ORM/Query/ResultSetMapping.php
@@ -168,6 +168,13 @@ class ResultSetMapping
      */
     public $metadataParameterMapping = [];
 
+    /**
+     * Contains query parameter names to be resolved as discriminator values
+     *
+     * @var array
+     */
+    public $discriminatorParameters = [];
+
     /**
      * Adds an entity result to this ResultSetMapping.
      *
diff --git a/lib/Doctrine/ORM/Query/SqlWalker.php b/lib/Doctrine/ORM/Query/SqlWalker.php
index 8c8ef30d1..3407b0a8b 100644
--- a/lib/Doctrine/ORM/Query/SqlWalker.php
+++ b/lib/Doctrine/ORM/Query/SqlWalker.php
@@ -2270,42 +2270,29 @@ class SqlWalker implements TreeWalker
     }
 
     /**
-     * @param ClassMetadataInfo $discrClass
+     * @param ClassMetadataInfo $rootClass
      * @param AST\InstanceOfExpression $instanceOfExpr
      * @return string The list in parentheses of valid child discriminators from the given class
      * @throws QueryException
      */
-    private function getChildDiscriminatorsFromClassMetadata(ClassMetadataInfo $discrClass, AST\InstanceOfExpression $instanceOfExpr)
+    private function getChildDiscriminatorsFromClassMetadata(ClassMetadataInfo $rootClass, AST\InstanceOfExpression $instanceOfExpr)
     {
         $sqlParameterList = [];
         $discriminators = [];
         foreach ($instanceOfExpr->value as $parameter) {
             if ($parameter instanceof AST\InputParameter) {
-                $this->rsm->addMetadataParameterMapping($parameter->name, 'discriminatorValue');
-
-                $sqlParameterList[] = $this->walkInputParameter($parameter);
-
+                $this->rsm->discriminatorParameters[$parameter->name] = $parameter->name;
+                $sqlParameterList[] = $this->walkInParameter($parameter);
                 continue;
             }
 
             $metadata = $this->em->getClassMetadata($parameter);
 
-            if ($metadata->getName() !== $discrClass->name && ! $metadata->getReflectionClass()->isSubclassOf($discrClass->name)) {
-                throw QueryException::instanceOfUnrelatedClass($parameter, $discrClass->name);
+            if ($metadata->getName() !== $rootClass->name && ! $metadata->getReflectionClass()->isSubclassOf($rootClass->name)) {
+                throw QueryException::instanceOfUnrelatedClass($parameter, $rootClass->name);
             }
 
-            // Include discriminators for parameter class and its subclass
-            $hierarchyClasses = $metadata->subClasses;
-            $hierarchyClasses[] = $metadata->name;
-
-            foreach ($hierarchyClasses as $class) {
-                $currentMetadata = $this->em->getClassMetadata($class);
-                $currentDiscriminator = $currentMetadata->discriminatorValue;
-
-                if (null !== $currentDiscriminator) {
-                    $discriminators[$currentDiscriminator] = null;
-                }
-            }
+            $discriminators = $discriminators + $this->getAllDiscriminators($metadata);
         }
 
         foreach (array_keys($discriminators) as $dis) {
@@ -2314,4 +2301,23 @@ class SqlWalker implements TreeWalker
 
         return '(' . implode(', ', $sqlParameterList) . ')';
     }
+
+    private function getAllDiscriminators(ClassMetadata $classMetadata)
+    {
+        // FIXME: this code is identical to Query->getAllDiscriminators()
+        $hierarchyClasses = $classMetadata->subClasses;
+        $hierarchyClasses[] = $classMetadata->name;
+
+        $discriminators = [];
+        foreach ($hierarchyClasses as $class) {
+            $currentMetadata = $this->em->getClassMetadata($class);
+            $currentDiscriminator = $currentMetadata->discriminatorValue;
+
+            if (null !== $currentDiscriminator) {
+                $discriminators[$currentDiscriminator] = null;
+            }
+        }
+
+        return $discriminators;
+    }
 }
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1995Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1995Test.php
index fb32b99fe..8bb975a05 100644
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1995Test.php
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1995Test.php
@@ -72,10 +72,9 @@ class DDC1995Test extends \Doctrine\Tests\OrmFunctionalTestCase
                 ->getResult();
 
         $this->assertCount(1, $result1);
-        $this->assertCount(1, $result2);
+        $this->assertCount(2, $result2);
 
         $this->assertInstanceOf(CompanyEmployee::class, $result1[0]);
-        $this->assertInstanceOf(CompanyPerson::class, $result2[0]);
-        $this->assertNotInstanceOf(CompanyEmployee::class, $result2[0]);
+        $this->assertContainsOnlyInstancesOf(CompanyPerson::class, $result2);
     }
 }