diff --git a/reactos/ntoskrnl/io/iomgr/device.c b/reactos/ntoskrnl/io/iomgr/device.c
index 78b7c598fb1..13e21e4f58e 100644
--- a/reactos/ntoskrnl/io/iomgr/device.c
+++ b/reactos/ntoskrnl/io/iomgr/device.c
@@ -1088,6 +1088,10 @@ IoEnumerateDeviceObjectList(IN  PDRIVER_OBJECT DriverObject,
 {
     ULONG ActualDevices = 1;
     PDEVICE_OBJECT CurrentDevice = DriverObject->DeviceObject;
+    KIRQL OldIrql;
+
+    /* Raise to dispatch level */
+    KeRaiseIrql(DISPATCH_LEVEL, &OldIrql);
 
     /* Find out how many devices we'll enumerate */
     while ((CurrentDevice = CurrentDevice->NextDevice)) ActualDevices++;
@@ -1099,13 +1103,14 @@ IoEnumerateDeviceObjectList(IN  PDRIVER_OBJECT DriverObject,
     *ActualNumberDeviceObjects = ActualDevices;
 
     /* Check if we can support so many */
-    if ((ActualDevices * 4) > DeviceObjectListSize)
+    if ((ActualDevices * sizeof(PDEVICE_OBJECT)) > DeviceObjectListSize)
     {
         /* Fail because the buffer was too small */
+        KeLowerIrql(OldIrql);
         return STATUS_BUFFER_TOO_SMALL;
     }
 
-    /* Check if the caller only wanted the size */
+    /* Check if the caller wanted the device list */
     if (DeviceObjectList)
     {
         /* Loop through all the devices */
@@ -1124,6 +1129,9 @@ IoEnumerateDeviceObjectList(IN  PDRIVER_OBJECT DriverObject,
         }
     }
 
+    /* Return back to previous IRQL */
+    KeLowerIrql(OldIrql);
+
     /* Return the status */
     return STATUS_SUCCESS;
 }