diff --git a/test/stdlib/StringIO_test.rb b/test/stdlib/StringIO_test.rb
index debf0800a..37121ea52 100644
--- a/test/stdlib/StringIO_test.rb
+++ b/test/stdlib/StringIO_test.rb
@@ -75,26 +75,11 @@ def test_read
                      StringIO.new("a"), :read, 1, nil
   end
 
-  def test_pread
-    assert_send_type "(::Integer, ::Integer, nil) -> ::String",
-                     StringIO.new("a"), :pread, 1, 0, nil
-  end
-
-  def test_read_nonblock
-    assert_send_type "(::int, nil) -> ::String?",
-                     StringIO.new("a"), :read_nonblock, 1, nil
-  end
-
   def test_readpartial
     assert_send_type "(::int, nil) -> ::String",
                      StringIO.new("a"), :readpartial, 1, nil
   end
 
-  def test_sysread
-    assert_send_type "(::Integer, nil) -> ::String",
-                     StringIO.new("a"), :sysread, 1, nil
-  end
-
   def test_truncate
     io = StringIO.new
 
@@ -135,6 +120,8 @@ def test_pread
                      StringIO.new("abcdef"), :pread, 3, 0
     assert_send_type "(Integer, Integer, String) -> String",
                      StringIO.new("abcdef"), :pread, 3, 0, +"buf"
+    assert_send_type "(::Integer, ::Integer, nil) -> ::String",
+                     StringIO.new("a"), :pread, 1, 0, nil
   end
 
   def test_read_nonblock
@@ -148,6 +135,8 @@ def test_read_nonblock
                      StringIO.new("abc"), :read_nonblock, 2, exception: false
     assert_send_type "(int, exception: false) -> nil",
                      StringIO.new(""), :read_nonblock, 2, exception: false
+    assert_send_type "(::int, nil) -> ::String?",
+                     StringIO.new("a"), :read_nonblock, 1, nil
   end
 
   def test_write_nonblock
@@ -164,6 +153,8 @@ def test_sysread
                      StringIO.new("abc"), :sysread, 2
     assert_send_type "(Integer, String) -> String",
                      StringIO.new("abc"), :sysread, 2, +"buf"
+    assert_send_type "(::Integer, nil) -> ::String",
+                     StringIO.new("a"), :sysread, 1, nil
   end
 
   def test_ungetc