diff --git a/test/csv/test_interface.rb b/test/csv/test_interface.rb
index 04d0edc5f1..a58e9c6179 100644
--- a/test/csv/test_interface.rb
+++ b/test/csv/test_interface.rb
@@ -167,14 +167,14 @@ class TestCSVInterface < Test::Unit::TestCase
     File.unlink(@path)
 
     lines = [{a: 1, b: 2, c: 3}, {a: 4, b: 5, c: 6}]
-    CSV.open( @path, "w", headers:           true,
-                          header_converters: :symbol ) do |csv|
+    CSV.open( @path, "wb", headers:           true,
+                           header_converters: :symbol ) do |csv|
       csv << lines.first.keys
       lines.each { |line| csv << line }
     end
-    CSV.open( @path, "r", headers:           true,
-                          converters:        :all,
-                          header_converters: :symbol ) do |csv|
+    CSV.open( @path, "rb", headers:           true,
+                           converters:        :all,
+                           header_converters: :symbol ) do |csv|
       csv.each { |line| assert_equal(lines.shift, line.to_hash) }
     end
   end
diff --git a/test/dl/test_func.rb b/test/dl/test_func.rb
index 3900af3d5f..ab8353bd76 100644
--- a/test/dl/test_func.rb
+++ b/test/dl/test_func.rb
@@ -22,8 +22,12 @@ module DL
     end
 
     def test_sinf
-      f = Function.new(CFunc.new(@libm['sinf'], TYPE_FLOAT, 'sinf'),
-                       [TYPE_FLOAT])
+      begin
+        f = Function.new(CFunc.new(@libm['sinf'], TYPE_FLOAT, 'sinf'),
+                         [TYPE_FLOAT])
+      rescue DL::DLError
+        skip "libm may not have sinf()"
+      end
       assert_in_delta 1.0, f.call(90 * Math::PI / 180), 0.0001
     end
 
diff --git a/test/win32ole/test_folderitem2_invokeverb.rb b/test/win32ole/test_folderitem2_invokeverb.rb
index e5380cacf7..89da49772c 100644
--- a/test/win32ole/test_folderitem2_invokeverb.rb
+++ b/test/win32ole/test_folderitem2_invokeverb.rb
@@ -64,7 +64,7 @@ if defined?(WIN32OLE)
       # is found in context menu,
       if @shortcut
         links = find_link(@dummy_path)
-        assert(0, links.size)
+        assert_equal(0, links.size)
 
         # Now create shortcut to @dummy_path
         arg = WIN32OLE_VARIANT.new(@shortcut)
@@ -72,7 +72,7 @@ if defined?(WIN32OLE)
 
         # Now search shortcut to @dummy_path
         links = find_link(@dummy_path)
-        assert(1, links.size)
+        assert_equal(1, links.size)
         @lpath = links[0].path
       end
     end