diff --git a/lib/tempfile.rb b/lib/tempfile.rb
index 36b0e1a481..38d6e5ce24 100644
--- a/lib/tempfile.rb
+++ b/lib/tempfile.rb
@@ -227,7 +227,7 @@ class Tempfile < DelegateClass(File)
     if !@tmpfile.closed?
       @tmpfile.size # File#size calls rb_io_flush_raw()
     else
-      File.size?(@tmpfile.path)
+      File.size(@tmpfile.path)
     end
   end
   alias length size
diff --git a/test/test_tempfile.rb b/test/test_tempfile.rb
index 2149aaf77c..a31ea67fd0 100644
--- a/test/test_tempfile.rb
+++ b/test/test_tempfile.rb
@@ -247,6 +247,13 @@ puts Tempfile.new('foo').path
     assert_equal 5, t.size
   end
 
+  def test_size_on_empty_file
+    t = tempfile("foo")
+    t.write("")
+    t.close
+    assert_equal 0, t.size
+  end
+
   def test_concurrency
     threads = []
     tempfiles = []
diff --git a/version.h b/version.h
index eb3d8b91b9..93f4bbb456 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.4.0"
-#define RUBY_RELEASE_DATE "2017-03-17"
-#define RUBY_PATCHLEVEL 105
+#define RUBY_RELEASE_DATE "2017-03-18"
+#define RUBY_PATCHLEVEL 106
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 3
-#define RUBY_RELEASE_DAY 17
+#define RUBY_RELEASE_DAY 18
 
 #include "ruby/version.h"