diff --git a/spec/ruby/command_line/dash_upper_e_spec.rb b/spec/ruby/command_line/dash_upper_e_spec.rb
index e39491ca8b..39ffa001a3 100644
--- a/spec/ruby/command_line/dash_upper_e_spec.rb
+++ b/spec/ruby/command_line/dash_upper_e_spec.rb
@@ -4,9 +4,11 @@ describe "ruby -E" do
     result.should == "EUC-JP"
   end
 
-  it "also sets the filesystem encoding with '-E external'" do
-    result = ruby_exe("print Encoding.find('filesystem')", options: '-E euc-jp')
-    result.should == "EUC-JP"
+  platform_is_not :windows do
+    it "also sets the filesystem encoding with '-E external'" do
+      result = ruby_exe("print Encoding.find('filesystem')", options: '-E euc-jp')
+      result.should == "EUC-JP"
+    end
   end
 
   it "sets the external encoding with '-E external:'" do
diff --git a/spec/ruby/core/encoding/default_external_spec.rb b/spec/ruby/core/encoding/default_external_spec.rb
index a4e2a3a61e..23f6c90f9b 100644
--- a/spec/ruby/core/encoding/default_external_spec.rb
+++ b/spec/ruby/core/encoding/default_external_spec.rb
@@ -35,9 +35,11 @@ with_feature :encoding do
       Encoding.find('external').should == Encoding::SHIFT_JIS
     end
 
-    it "also sets the filesystem encoding" do
-      Encoding.default_external = Encoding::SHIFT_JIS
-      Encoding.find('filesystem').should == Encoding::SHIFT_JIS
+    platform_is_not :windows do
+      it "also sets the filesystem encoding" do
+        Encoding.default_external = Encoding::SHIFT_JIS
+        Encoding.find('filesystem').should == Encoding::SHIFT_JIS
+      end
     end
 
     it "can accept a name of an encoding as a String" do