diff --git a/src/Mount/Mount.c b/src/Mount/Mount.c
index 609dbbf3..93d5fd71 100644
--- a/src/Mount/Mount.c
+++ b/src/Mount/Mount.c
@@ -6328,9 +6328,10 @@ retry:
 		return FALSE;
 
 	memset (&mountList, 0, sizeof (mountList));
-	if (	DeviceIoControl (hDriver, TC_IOCTL_GET_MOUNTED_VOLUMES, &mountList, sizeof (mountList), &mountList, sizeof (mountList), &dwResult, NULL)
-		&& (mountList.ulMountedDrives < (1 << 26))
-		)
+	status = DeviceIoControl (hDriver, TC_IOCTL_GET_MOUNTED_VOLUMES, &mountList, sizeof (mountList), &mountList, sizeof (mountList), &dwResult, NULL)
+		&& (dwResult == sizeof (mountList))
+		&& (mountList.ulMountedDrives < (1 << 26));
+	if (status)
 	{
 		// remove any custom label from registry
 		if (prevMountList.ulMountedDrives)
@@ -6345,14 +6346,16 @@ retry:
 		}
 	}
 
-	BroadcastDeviceChange (DBT_DEVICEREMOVECOMPLETE, 0, prevMountList.ulMountedDrives & ~mountList.ulMountedDrives);
+	// A failed query doesn't mean that every volume was dismounted.
+	DWORD removedDrives = status ? prevMountList.ulMountedDrives & ~mountList.ulMountedDrives : 0;
+	if (removedDrives)
+		BroadcastDeviceChange (DBT_DEVICEREMOVECOMPLETE, 0, removedDrives);
 
 	/* GH #337, GH #1426: Flush shell notifications synchronously in
 	   silent/CLI mode to prevent ghost drive letters when the process
 	   exits immediately after dismount. */
 	if (Silent && !DeviceChangeBroadcastDisabled)
 	{
-		DWORD removedDrives = prevMountList.ulMountedDrives & ~mountList.ulMountedDrives;
 		for (i = 0; i < 26; i++)
 		{
 			if (removedDrives & (1 << i))
@@ -6405,7 +6408,7 @@ retry:
 	}
 	else
 	{
-		if (bBeep)
+		if (bBeep && status)
 			MessageBeep (0xFFFFFFFF);
 	}