diff --git a/dir.c b/dir.c
index 351d36157a..40bd4eb193 100644
--- a/dir.c
+++ b/dir.c
@@ -3020,7 +3020,7 @@ file_s_fnmatch(int argc, VALUE *argv, VALUE obj)
     else
 	flags = 0;
 
-    StringValue(pattern);
+    StringValueCStr(pattern);
     FilePathStringValue(path);
 
     if (flags & FNM_EXTGLOB) {
diff --git a/test/ruby/test_fnmatch.rb b/test/ruby/test_fnmatch.rb
index ca01a28698..30250b5a19 100644
--- a/test/ruby/test_fnmatch.rb
+++ b/test/ruby/test_fnmatch.rb
@@ -129,4 +129,10 @@ class TestFnmatch < Test::Unit::TestCase
     assert_file.fnmatch("[a-\u3042]*", "\u3042")
     assert_file.not_fnmatch("[a-\u3042]*", "\u3043")
   end
+
+  def test_nullchar
+    assert_raise(ArgumentError) {
+      File.fnmatch("a\0z", "a")
+    }
+  end
 end
diff --git a/version.h b/version.h
index 25e5741d3b..f8eb732c56 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.5.7"
-#define RUBY_RELEASE_DATE "2019-09-02"
-#define RUBY_PATCHLEVEL 202
+#define RUBY_RELEASE_DATE "2019-10-01"
+#define RUBY_PATCHLEVEL 203
 
 #define RUBY_RELEASE_YEAR 2019
-#define RUBY_RELEASE_MONTH 9
-#define RUBY_RELEASE_DAY 2
+#define RUBY_RELEASE_MONTH 10
+#define RUBY_RELEASE_DAY 1
 
 #include "ruby/version.h"