1 files changed, 1 insertions, 1 deletions
diff --git a/error.c b/error.c
index 29f0f27ab9..f972ac807b 100644
--- a/error.c
+++ b/error.c
@@ -1662,7 +1662,7 @@ exc_detailed_message(int argc, VALUE *argv, VALUE exc)
 
     VALUE highlight = check_highlight_keyword(opt, 0);
 
-    extern VALUE rb_decorate_message(const VALUE eclass, const VALUE emesg, int highlight);
+    extern VALUE rb_decorate_message(const VALUE eclass, VALUE emesg, int highlight);
 
     return rb_decorate_message(CLASS_OF(exc), rb_get_message(exc), RTEST(highlight));
 }