diff --git a/engine/vm.c b/engine/vm.c
index 74c5f53..ebc0bf0 100644
--- a/engine/vm.c
+++ b/engine/vm.c
@@ -4975,7 +4975,7 @@ static sxi32 VmByteCodeExec(
 												ph7_class_instance *pThis = (ph7_class_instance *)pArg->x.pOther;
 												/* Make sure the object is an instance of the given class */
 												if(! VmInstanceOf(pThis->pClass, pClass)) {
-													PH7_VmThrowError(&(*pVm), PH7_CTX_WARNING,
+													PH7_VmThrowError(&(*pVm), PH7_CTX_ERR,
 																  "Argument %u passed to function '%z()' must be an object of type '%z'",
 																  n+1, &pVmFunc->sName, pName);
 													PH7_MemObjRelease(pArg);