--- a/ext/date/date_parse.c
+++ b/ext/date/date_parse.c
@@ -569,7 +569,7 @@ date_zone_to_diff(VALUE str)
                        if (cl >= 3)
                            min  = rb_str_new(&cs[1], 2);
                        if (cl >= 5)
-                           min  = rb_str_new(&cs[3], 2);
+                           sec  = rb_str_new(&cs[3], 2);
                    }
                    else {
                        if (cl >= 2)