diff --git a/compiler/commands.nim b/compiler/commands.nim
index 87e94d9c9d..cea965f5c3 100644
--- a/compiler/commands.nim
+++ b/compiler/commands.nim
@@ -393,7 +393,9 @@ proc processSwitch(switch, arg: string, pass: TCmdLinePass, info: TLineInfo) =
   of "linedir": processOnOffSwitch({optLineDir}, arg, pass, info)
   of "assertions", "a": processOnOffSwitch({optAssert}, arg, pass, info)
   of "deadcodeelim": processOnOffSwitchG({optDeadCodeElim}, arg, pass, info)
-  of "threads": processOnOffSwitchG({optThreads}, arg, pass, info)
+  of "threads":
+    processOnOffSwitchG({optThreads}, arg, pass, info)
+    if optThreads in gGlobalOptions: incl(gNotes, warnGcUnsafe)
   of "tlsemulation": processOnOffSwitchG({optTlsEmulation}, arg, pass, info)
   of "taintmode": processOnOffSwitchG({optTaintMode}, arg, pass, info)
   of "implicitstatic":