diff --git a/packaging/windows/farmcontrol.nsi b/packaging/windows/farmcontrol.nsi
index 37586c2..642a26a 100644
--- a/packaging/windows/farmcontrol.nsi
+++ b/packaging/windows/farmcontrol.nsi
@@ -115,7 +115,12 @@ Section "Farm Control" SecMain
 
   WriteUninstaller "$INSTDIR\Uninstall.exe"
 
-  !insertmacro progressSuccess
+  ; For in-app updates (/RESTARTFC) the success signal is emitted from
+  ; restartFarmControlAfterUpdate, right before the install directory swap,
+  ; so the running app quits while this installer stays alive.
+  ${If} $RestartAfterInstall != "1"
+    !insertmacro progressSuccess
+  ${EndIf}
 SectionEnd
 
 Section "Uninstall"
diff --git a/packaging/windows/installer.nsh b/packaging/windows/installer.nsh
index 940f557..14b5255 100644
--- a/packaging/windows/installer.nsh
+++ b/packaging/windows/installer.nsh
@@ -304,8 +304,14 @@ Function restartFarmControlAfterUpdate
     Return
   ${EndIf}
 
+  ; All files are copied and we are about to rename the install directory.
+  ; Emit the success line (matched by isWindowsInstallSuccessful in
+  ; winappupdate.js) so the app knows to quit and restart; this installer
+  ; stays alive to swap the folders and relaunch Farm Control.
+  !insertmacro progressSuccess
+
   !insertmacro progressStatus "Waiting for Farm Control to close..."
-  Sleep 1000
+  Sleep 1500
 
   restart_wait_loop:
     ExecWait 'cmd.exe /c tasklist /FI "IMAGENAME eq FarmControl.exe" 2>nul | find /I "FarmControl.exe"' $R0