diff --git a/lib/textbringer/window.rb b/lib/textbringer/window.rb
index 921a9eb..b4be844 100644
--- a/lib/textbringer/window.rb
+++ b/lib/textbringer/window.rb
@@ -2,45 +2,8 @@
 
 require "curses"
 require "unicode/display_width"
-require "fiddle/import"
 
 module Textbringer
-  # These features should be provided by curses.gem.
-  module PDCurses
-    KEY_OFFSET = 0xec00
-    ALT_0 = KEY_OFFSET + 0x97
-    ALT_9 = KEY_OFFSET + 0xa0
-    ALT_A = KEY_OFFSET + 0xa1
-    ALT_Z = KEY_OFFSET + 0xba
-    ALT_NUMBER_BASE = ALT_0 - ?0.ord
-    ALT_ALPHA_BASE = ALT_A - ?a.ord
-
-    KEY_MODIFIER_SHIFT   = 1
-    KEY_MODIFIER_CONTROL = 2
-    KEY_MODIFIER_ALT     = 4
-    KEY_MODIFIER_NUMLOCK = 8
-
-    @dll_loaded = false
-
-    class << self
-      attr_writer :dll_loaded
-
-      def dll_loaded?
-        @dll_loaded
-      end
-    end
-
-    begin
-      extend Fiddle::Importer
-      dlload "pdcurses.dll"
-      extern "unsigned long PDC_get_key_modifiers(void)"
-      extern "int PDC_save_key_modifiers(unsigned char)"
-      extern "int PDC_return_key_modifiers(unsigned char)"
-      @dll_loaded = true
-    rescue Fiddle::DLError
-    end
-  end
-
   class Window
     KEY_NAMES = {}
     Curses.constants.grep(/\AKEY_/).each do |name|
@@ -48,6 +11,12 @@ class Window
         name.slice(/\AKEY_(.*)/, 1).downcase.intern
     end
 
+    HAVE_GET_KEY_MODIFIERS = defined?(Curses.get_key_modifiers)
+    if HAVE_GET_KEY_MODIFIERS
+      ALT_NUMBER_BASE = Curses::ALT_0 - ?0.ord
+      ALT_ALPHA_BASE = Curses::ALT_A - ?a.ord
+    end
+
     @@started = false
     @@list = []
     @@current = nil
@@ -325,12 +294,12 @@ def current?
     def read_event
       key = get_char
       if key.is_a?(Integer)
-        if PDCurses.dll_loaded?
-          if PDCurses::ALT_0 <= key && key <= PDCurses::ALT_9
-            @key_buffer.push((key - PDCurses::ALT_NUMBER_BASE).chr)
+        if HAVE_GET_KEY_MODIFIERS
+          if Curses::ALT_0 <= key && key <= Curses::ALT_9
+            @key_buffer.push((key - ALT_NUMBER_BASE).chr)
             return "\e"
-          elsif PDCurses::ALT_A <= key && key <= PDCurses::ALT_Z
-            @key_buffer.push((key - PDCurses::ALT_ALPHA_BASE).chr)
+          elsif Curses::ALT_A <= key && key <= Curses::ALT_Z
+            @key_buffer.push((key - ALT_ALPHA_BASE).chr)
             return "\e"
           end
         end
@@ -780,7 +749,7 @@ def delete_marks
 
     def get_char
       if @key_buffer.empty?
-        PDCurses.PDC_save_key_modifiers(1) if PDCurses.dll_loaded?
+        Curses.save_key_modifiers(true) if HAVE_GET_KEY_MODIFIERS
         begin
           need_retry = false
           if @raw_key_buffer.empty?
@@ -788,13 +757,13 @@ def get_char
           else
             key = @raw_key_buffer.shift
           end
-          if PDCurses.dll_loaded?
-            mods = PDCurses.PDC_get_key_modifiers
+          if HAVE_GET_KEY_MODIFIERS
+            mods = Curses.get_key_modifiers
             if key.is_a?(String) && key.ascii_only?
-              if (mods & PDCurses::KEY_MODIFIER_CONTROL) != 0
+              if (mods & Curses::PDC_KEY_MODIFIER_CONTROL) != 0
                 key = key == ?? ? "\x7f" : (key.ord & 0x9f).chr
               end
-              if (mods & PDCurses::KEY_MODIFIER_ALT) != 0
+              if (mods & Curses::PDC_KEY_MODIFIER_ALT) != 0
                 if key == "\0"
                   # Alt + `, Alt + < etc. return NUL, so ignore it.
                   need_retry = true
diff --git a/test/test_helper.rb b/test/test_helper.rb
index bb131d0..aa9f70d 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,6 +1,7 @@
 require "simplecov"
 require "test/unit"
 require "tmpdir"
+require "curses"
 
 SimpleCov.profiles.define "textbringer" do
   add_filter "/test/"
@@ -26,6 +27,36 @@ def format(*args)
   SimpleCov.formatter = SimpleCov::Formatter::Codecov
 end
 
+module Curses
+  if !defined?(Curses.get_key_modifiers)
+    @key_modifiers = 0
+
+    def self.save_key_modifiers(flag)
+    end
+
+    def self.get_key_modifiers
+      @key_modifiers
+    end
+
+    def self.set_key_modifiers(key_modifiers)
+      @key_modifiers = key_modifiers
+    end
+
+    KEY_OFFSET = 0xec00
+    ALT_0 = KEY_OFFSET + 0x97
+    ALT_9 = KEY_OFFSET + 0xa0
+    ALT_A = KEY_OFFSET + 0xa1
+    ALT_Z = KEY_OFFSET + 0xba
+    ALT_NUMBER_BASE = ALT_0 - ?0.ord
+    ALT_ALPHA_BASE = ALT_A - ?a.ord
+
+    PDC_KEY_MODIFIER_SHIFT   = 1
+    PDC_KEY_MODIFIER_CONTROL = 2
+    PDC_KEY_MODIFIER_ALT     = 4
+    PDC_KEY_MODIFIER_NUMLOCK = 8
+  end
+end
+
 require "textbringer"
 
 module Curses
@@ -190,23 +221,6 @@ def method_missing(mid, *args)
   end
   ::Curses.send(:remove_const, :Window)
   ::Curses.const_set(:Window, FakeCursesWindow)
-
-  module PDCurses
-    self.dll_loaded = true
-
-    @key_modifiers = 0
-
-    def PDCurses.PDC_save_key_modifiers(flag)
-    end
-
-    def PDCurses.PDC_get_key_modifiers
-      @key_modifiers
-    end
-
-    def PDCurses.PDC_set_key_modifiers(key_modifiers)
-      @key_modifiers = key_modifiers
-    end
-  end
   
   class Window
     class << self
diff --git a/test/textbringer/test_window.rb b/test/textbringer/test_window.rb
index fe5355d..717afda 100644
--- a/test/textbringer/test_window.rb
+++ b/test/textbringer/test_window.rb
@@ -233,27 +233,27 @@ def test_read_event
     @window.window.push_key(Curses::KEY_RIGHT)
     assert_equal(:right, @window.read_event)
 
-    @window.window.push_key(PDCurses::ALT_0 + 3)
+    @window.window.push_key(Curses::ALT_0 + 3)
     assert_equal("\e", @window.read_event)
     assert_equal("3", @window.read_event)
 
-    @window.window.push_key(PDCurses::ALT_A + 5)
+    @window.window.push_key(Curses::ALT_A + 5)
     assert_equal("\e", @window.read_event)
     assert_equal("f", @window.read_event)
 
-    PDCurses.PDC_set_key_modifiers(PDCurses::KEY_MODIFIER_CONTROL)
+    Curses.set_key_modifiers(Curses::PDC_KEY_MODIFIER_CONTROL)
     @window.window.push_key("a")
     assert_equal("\C-a", @window.read_event)
     @window.window.push_key("?")
     assert_equal("\x7f", @window.read_event)
 
-    PDCurses.PDC_set_key_modifiers(PDCurses::KEY_MODIFIER_ALT)
+    Curses.set_key_modifiers(Curses::PDC_KEY_MODIFIER_ALT)
     @window.window.push_key("\0")
     @window.window.push_key("a")
     assert_equal("\e", @window.read_event)
     assert_equal("a", @window.read_event)
   ensure
-    PDCurses.PDC_set_key_modifiers(0)
+    Curses.set_key_modifiers(0)
   end
 
   def test_read_event_nonblock
@@ -267,13 +267,13 @@ def test_wait_input
     @window.window.push_key("a")
     assert_equal("a", @window.wait_input(1))
 
-    PDCurses.PDC_set_key_modifiers(PDCurses::KEY_MODIFIER_ALT)
+    Curses.set_key_modifiers(Curses::PDC_KEY_MODIFIER_ALT)
     @window.window.push_key("\0")
     @window.window.push_key("a")
     assert_equal("\e", @window.read_event)
     assert_equal("a", @window.wait_input(1))
   ensure
-    PDCurses.PDC_set_key_modifiers(0)
+    Curses.set_key_modifiers(0)
   end
 
   def test_has_input?
@@ -282,13 +282,13 @@ def test_has_input?
     @window.window.push_key("a")
     assert_equal(true, @window.has_input?)
 
-    PDCurses.PDC_set_key_modifiers(PDCurses::KEY_MODIFIER_ALT)
+    Curses.set_key_modifiers(Curses::PDC_KEY_MODIFIER_ALT)
     @window.window.push_key("\0")
     @window.window.push_key("a")
     assert_equal("\e", @window.read_event)
     assert_equal(true, @window.has_input?)
   ensure
-    PDCurses.PDC_set_key_modifiers(0)
+    Curses.set_key_modifiers(0)
   end
 
   def test_echo_area_redisplay
diff --git a/textbringer.gemspec b/textbringer.gemspec
index bff646e..95a6f70 100644
--- a/textbringer.gemspec
+++ b/textbringer.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.3'
 
-  spec.add_runtime_dependency "curses", "~> 1.2"
+  spec.add_runtime_dependency "curses", ">= 1.2.2"
   spec.add_runtime_dependency "unicode-display_width", "~> 1.1"
   spec.add_runtime_dependency "clipboard", "~> 1.1"
   spec.add_runtime_dependency "fiddley", ">= 0.0.5"