diff --git a/src/crystal/system/dir_handle.cr b/src/crystal/system/dir_handle.cr
new file mode 100644
index 000000000000..38c3e650fd0f
--- /dev/null
+++ b/src/crystal/system/dir_handle.cr
@@ -0,0 +1,35 @@
+struct Crystal::System::DirHandle
+  # Creates a new `DirHandle`
+  # def self.new(path : String) : DirHandle
+
+  # Reads the next entry from dir and returns it as a string. Returns `nil` at the end of the stream.
+  # def read
+
+  # Repositions this directory to the first entry.
+  # def rewind
+
+  # Closes the directory stream.
+  # def close
+
+  # Returns the current working directory.
+  # def self.current : String
+
+  # Changes the current working directory of the process to the given string.
+  # def self.cd(path : String)
+
+  # Returns `true` if the given path exists and is a directory
+  # def self.exists?(path : String) : Bool
+
+  # Creates a new directory at the given path, including any non-existing
+  # intermediate directories. The linux-style permission mode can be specified.
+  # def self.mkdir(path : String, mode)
+
+  # Removes the directory at the given path.
+  # def self.rmdir(path : String)
+end
+
+{% if flag?(:win32) %}
+  require "./windows/dir_handle"
+{% else %}
+  require "./unix/dir_handle"
+{% end %}
diff --git a/src/crystal/system/unix/dir_handle.cr b/src/crystal/system/unix/dir_handle.cr
new file mode 100644
index 000000000000..f0c7eb20f2f0
--- /dev/null
+++ b/src/crystal/system/unix/dir_handle.cr
@@ -0,0 +1,79 @@
+require "c/dirent"
+require "c/unistd"
+require "c/sys/stat"
+
+struct Crystal::System::DirHandle
+  @dirhandle : LibC::DIR*
+
+  @closed = false
+
+  def initialize(path : String)
+    @dirhandle = LibC.opendir(path.check_no_null_byte)
+    unless @dirhandle
+      raise Errno.new("Error opening directory '#{path}'")
+    end
+    @closed = false
+  end
+
+  def read
+    # readdir() returns NULL for failure and sets errno or returns NULL for EOF but leaves errno as is.  wtf.
+    Errno.value = 0
+    ent = LibC.readdir(@dirhandle)
+    if ent
+      String.new(ent.value.d_name.to_unsafe)
+    elsif Errno.value != 0
+      raise Errno.new("readdir")
+    else
+      nil
+    end
+  end
+
+  def rewind
+    LibC.rewinddir(@dirhandle)
+  end
+
+  def close
+    return if @closed
+    if LibC.closedir(@dirhandle) != 0
+      raise Errno.new("closedir")
+    end
+    @closed = true
+  end
+
+  def self.current : String
+    if dir = LibC.getcwd(nil, 0)
+      String.new(dir).tap { LibC.free(dir.as(Void*)) }
+    else
+      raise Errno.new("getcwd")
+    end
+  end
+
+  def self.cd(path : String)
+    if LibC.chdir(path.check_no_null_byte) != 0
+      raise Errno.new("Error while changing directory to #{path.inspect}")
+    end
+  end
+
+  def self.exists?(path : String) : Bool
+    if LibC.stat(path.check_no_null_byte, out stat) != 0
+      if Errno.value == Errno::ENOENT || Errno.value == Errno::ENOTDIR
+        return false
+      else
+        raise Errno.new("stat")
+      end
+    end
+    File::Stat.new(stat).directory?
+  end
+
+  def self.mkdir(path : String, mode)
+    if LibC.mkdir(path.check_no_null_byte, mode) == -1
+      raise Errno.new("Unable to create directory '#{path}'")
+    end
+  end
+
+  def self.rmdir(path : String)
+    if LibC.rmdir(path.check_no_null_byte) == -1
+      raise Errno.new("Unable to remove directory '#{path}'")
+    end
+  end
+end
diff --git a/src/crystal/system/windows/dir_handle.cr b/src/crystal/system/windows/dir_handle.cr
new file mode 100644
index 000000000000..831c4cfd4ecf
--- /dev/null
+++ b/src/crystal/system/windows/dir_handle.cr
@@ -0,0 +1,83 @@
+require "c/winapi"
+require "winerror"
+
+struct Crystal::System::DirHandle
+  @dir_handle : LibC::Handle
+
+  def initialize(path : String)
+    if !DirHandle.exists?(path)
+      raise WinError.new("Error opening directory '#{path}'")
+    end
+    @dir_handle = LibC::INVALID_HANDLE_VALUE
+  end
+
+  def read
+    data = LibC::WIN32_FIND_DATA_A.new
+    if @dir_handle == LibC::INVALID_HANDLE_VALUE
+      @dir_handle = LibC._FindFirstFileA((path + "\\*").check_no_null_byte, pointerof(data))
+      if @dir_handle == LibC::INVALID_HANDLE_VALUE
+        raise WinError.new("FindFirstFileA")
+      end
+    elsif LibC._FindNextFileA(@dir_handle, pointerof(data)) == 0
+      error = LibC._GetLastError
+      if error == WinError::ERROR_NO_MORE_FILES
+        return nil
+      else
+        raise WinError.new("FindNextFileA", error)
+      end
+    end
+    String.new(data.cFileName.to_slice)
+  end
+
+  def rewind
+    close
+  end
+
+  def close
+    if @dir_handle != LibC::INVALID_HANDLE_VALUE
+      if LibC._FindClose(@dir_handle) == 0
+        raise WinError.new("FindClose")
+      end
+      @dir_handle = LibC::INVALID_HANDLE_VALUE
+    end
+  end
+
+  def self.current : String
+    len = LibC._GetCurrentDirectoryA(0, nil)
+    if len == 0
+      raise WinError.new("_GetCurrentDirectoryA")
+    end
+    String.new(len) do |buffer|
+      if LibC._GetCurrentDirectoryA(len, buffer) == 0
+        raise WinError.new("_GetCurrentDirectoryA")
+      end
+      {len - 1, len - 1} # remove \0 at the end
+    end
+  end
+
+  def self.cd(path : String)
+    if LibC._SetCurrentDirectoryA(path.check_no_null_byte) == 0
+      raise WinError.new("Error while changing directory to #{path.inspect}")
+    end
+  end
+
+  def self.exists?(path : String) : Bool
+    atr = LibC._GetFileAttributesA(path.check_no_null_byte)
+    if (atr == LibWindows::INVALID_FILE_ATTRIBUTES)
+      return false
+    end
+    return atr & LibC::FILE_ATTRIBUTE_DIRECTORY != 0
+  end
+
+  def self.mkdir(path : String, mode)
+    if LibC._CreateDirectoryA(path.check_no_null_byte, nil) == 0
+      raise WinError.new("Unable to create directory '#{path}'")
+    end
+  end
+
+  def self.rmdir(path : String)
+    if LibC._RemoveDirectoryA(path.check_no_null_byte) == 0
+      raise WinError.new("Unable to remove directory '#{path}'")
+    end
+  end
+end
diff --git a/src/dir.cr b/src/dir.cr
index 48f69dcce621..b5f5c1b5b81d 100644
--- a/src/dir.cr
+++ b/src/dir.cr
@@ -1,6 +1,4 @@
-require "c/dirent"
-require "c/unistd"
-require "c/sys/stat"
+require "crystal/system/dir_handle"
 
 # Objects of class `Dir` are directory streams representing directories in the underlying file system.
 # They provide a variety of ways to list directories and their contents.
@@ -17,11 +15,7 @@ class Dir
 
   # Returns a new directory object for the named directory.
   def initialize(@path)
-    @dir = LibC.opendir(@path.check_no_null_byte)
-    unless @dir
-      raise Errno.new("Error opening directory '#{@path}'")
-    end
-    @closed = false
+    @dir = Crystal::System::DirHandle.new(@path)
   end
 
   # Alias for `new(path)`
@@ -125,47 +119,28 @@ class Dir
   # array.sort # => [".", "..", "config.h"]
   # ```
   def read
-    # readdir() returns NULL for failure and sets errno or returns NULL for EOF but leaves errno as is.  wtf.
-    Errno.value = 0
-    ent = LibC.readdir(@dir)
-    if ent
-      String.new(ent.value.d_name.to_unsafe)
-    elsif Errno.value != 0
-      raise Errno.new("readdir")
-    else
-      nil
-    end
+    @dir.read
   end
 
   # Repositions this directory to the first entry.
   def rewind
-    LibC.rewinddir(@dir)
+    @dir.rewind
     self
   end
 
   # Closes the directory stream.
   def close
-    return if @closed
-    if LibC.closedir(@dir) != 0
-      raise Errno.new("closedir")
-    end
-    @closed = true
+    @dir.close
   end
 
   # Returns the current working directory.
   def self.current : String
-    if dir = LibC.getcwd(nil, 0)
-      String.new(dir).tap { LibC.free(dir.as(Void*)) }
-    else
-      raise Errno.new("getcwd")
-    end
+    Crystal::System::DirHandle.current
   end
 
   # Changes the current working directory of the process to the given string.
   def self.cd(path)
-    if LibC.chdir(path.check_no_null_byte) != 0
-      raise Errno.new("Error while changing directory to #{path.inspect}")
-    end
+    Crystal::System::DirHandle.cd(path)
   end
 
   # Changes the current working directory of the process to the given string
@@ -215,14 +190,7 @@ class Dir
 
   # Returns `true` if the given path exists and is a directory
   def self.exists?(path) : Bool
-    if LibC.stat(path.check_no_null_byte, out stat) != 0
-      if Errno.value == Errno::ENOENT || Errno.value == Errno::ENOTDIR
-        return false
-      else
-        raise Errno.new("stat")
-      end
-    end
-    File::Stat.new(stat).directory?
+    Crystal::System::DirHandle.exists?(path)
   end
 
   # Returns `true` if the directory at *path* is empty, otherwise returns `false`.
@@ -246,9 +214,7 @@ class Dir
   # Creates a new directory at the given path. The linux-style permission mode
   # can be specified, with a default of 777 (0o777).
   def self.mkdir(path, mode = 0o777)
-    if LibC.mkdir(path.check_no_null_byte, mode) == -1
-      raise Errno.new("Unable to create directory '#{path}'")
-    end
+    Crystal::System::DirHandle.mkdir(path, mode)
     0
   end
 
@@ -276,9 +242,7 @@ class Dir
 
   # Removes the directory at the given path.
   def self.rmdir(path)
-    if LibC.rmdir(path.check_no_null_byte) == -1
-      raise Errno.new("Unable to remove directory '#{path}'")
-    end
+    Crystal::System::DirHandle.rmdir(path)
     0
   end