diff --git a/spec/ruby/core/thread/kill_spec.rb b/spec/ruby/core/thread/kill_spec.rb
index 2c58475f8f..f932bf5232 100644
--- a/spec/ruby/core/thread/kill_spec.rb
+++ b/spec/ruby/core/thread/kill_spec.rb
@@ -2,20 +2,24 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/exit'
 
-describe "Thread#kill" do
-  it_behaves_like :thread_exit, :kill
-end
+# This spec randomly kills mspec worker like: https://ci.appveyor.com/project/ruby/ruby/builds/19473223/job/f69derxnlo09xhuj
+# TODO: Investigate the cause or at least print helpful logs, and remove this `platform_is_not` guard.
+platform_is_not :mingw do
+  describe "Thread#kill" do
+    it_behaves_like :thread_exit, :kill
+  end
 
-describe "Thread#kill!" do
-  it "needs to be reviewed for spec completeness"
-end
+  describe "Thread#kill!" do
+    it "needs to be reviewed for spec completeness"
+  end
 
-describe "Thread.kill" do
-  it "causes the given thread to exit" do
-    thread = Thread.new { sleep }
-    Thread.pass while thread.status and thread.status != "sleep"
-    Thread.kill(thread).should == thread
-    thread.join
-    thread.status.should be_false
+  describe "Thread.kill" do
+    it "causes the given thread to exit" do
+      thread = Thread.new { sleep }
+      Thread.pass while thread.status and thread.status != "sleep"
+      Thread.kill(thread).should == thread
+      thread.join
+      thread.status.should be_false
+    end
   end
 end