diff --git a/src/posix/platform/settings.cpp b/src/posix/platform/settings.cpp
index 3b4c2fd56..8ef12ffab 100644
--- a/src/posix/platform/settings.cpp
+++ b/src/posix/platform/settings.cpp
@@ -232,6 +232,7 @@ void otPlatSettingsDeinit(otInstance *aInstance)
 
     VerifyOrExit(sSettingsFd != -1);
     VerifyOrDie(close(sSettingsFd) == 0, OT_EXIT_ERROR_ERRNO);
+    sSettingsFd = -1;
 
 exit:
     return;