diff --git a/src/Analyser/TypeSpecifier.php b/src/Analyser/TypeSpecifier.php
index ebc025d4640..ee7b805c01e 100644
--- a/src/Analyser/TypeSpecifier.php
+++ b/src/Analyser/TypeSpecifier.php
@@ -275,6 +275,7 @@ public function specifyTypesInCondition(
 					&& strtolower((string) $exprNode->name) === 'get_parent_class'
 					&& isset($exprNode->getArgs()[0])
 					&& $constantType instanceof ConstantStringType
+					&& $constantType->getValue() !== ''
 				) {
 					$argType = $scope->getType($exprNode->getArgs()[0]->value);
 					$objectType = new ObjectType($constantType->getValue());
@@ -300,15 +301,14 @@ public function specifyTypesInCondition(
 						);
 					}
 
-					if ($argType instanceof MixedType) {
-						return $this->create(
-							$exprNode->getArgs()[0]->value,
-							TypeCombinator::union($objectType, $classStringType),
-							$context,
-							false,
-							$scope,
-						);
-					}
+				    return $this->create(
+						$exprNode->getArgs()[0]->value,
+						TypeCombinator::union($objectType, $classStringType),
+						$context,
+						false,
+						$scope,
+					);
+
 				}
 			}