diff --git a/src/Type/UnionType.php b/src/Type/UnionType.php
index b58890a9fb..f1b7f93223 100644
--- a/src/Type/UnionType.php
+++ b/src/Type/UnionType.php
@@ -85,6 +85,8 @@ class UnionType implements CompoundType
 
 	private ?TrinaryLogic $isNull = null;
 
+	private ?TrinaryLogic $isCallable = null;
+
 	/**
 	 * @api
 	 * @param list<Type> $types
@@ -1126,7 +1128,7 @@ public function getEnumCaseObject(): ?EnumCaseObjectType
 
 	public function isCallable(): TrinaryLogic
 	{
-		return $this->unionResults(static fn (Type $type): TrinaryLogic => $type->isCallable());
+		return $this->isCallable ??= $this->unionResults(static fn (Type $type): TrinaryLogic => $type->isCallable());
 	}
 
 	public function getCallableParametersAcceptors(ClassMemberAccessAnswerer $scope): array