diff --git a/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php b/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php
index 1eca983be1..f4d6f2f1ae 100644
--- a/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php
+++ b/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php
@@ -66,6 +66,7 @@ public function isFunctionSupported(FunctionReflection $functionReflection): boo
 			'is_string',
 			'is_subclass_of',
 			'is_a',
+			'is_countable',
 		], true);
 	}