diff --git a/build/Gruntfile.coffee b/build/Gruntfile.coffee
index 18915985e..bae4a53c4 100644
--- a/build/Gruntfile.coffee
+++ b/build/Gruntfile.coffee
@@ -47,7 +47,7 @@ module.exports = (grunt) ->
     contentsDir = shellAppDir
     appDir = path.join(shellAppDir, 'resources', 'app')
     installDir ?= path.join(process.env.ProgramFiles, appName)
-    killCommand = 'taskkill /FIM atom.exe'
+    killCommand = 'taskkill /F /IM atom.exe'
   else if process.platform is 'darwin'
     contentsDir = path.join(shellAppDir, 'Contents')
     appDir = path.join(contentsDir, 'Resources', 'app')
diff --git a/build/tasks/codesign-task.coffee b/build/tasks/codesign-task.coffee
index ab7ca23a7..7f579cbca 100644
--- a/build/tasks/codesign-task.coffee
+++ b/build/tasks/codesign-task.coffee
@@ -28,7 +28,7 @@ module.exports = (grunt) ->
         args = ['-f', '-v', '-s', 'Developer ID Application: GitHub', grunt.config.get('atom.shellAppDir')]
         spawn {cmd, args}, (error) -> callback(error)
       when 'win32'
-        spawn {cmd: 'taskkill', args: ['/FIM', 'atom.exe']}, ->
+        spawn {cmd: 'taskkill', args: ['/F', '/IM', 'atom.exe']}, ->
           cmd = process.env.JANKY_SIGNTOOL ? 'signtool'
           args = [path.join(grunt.config.get('atom.shellAppDir'), 'atom.exe')]
           spawn {cmd, args}, (error) -> callback(error)