1 files changed, 1 insertions, 1 deletions
diff --git a/proc.c b/proc.c
index f4ce8382b8..32b7ef8c44 100644
--- a/proc.c
+++ b/proc.c
@@ -427,7 +427,7 @@ proc_new(VALUE klass, int is_lambda)
 	}
 	else {
 	    VALUE newprocval = proc_dup(procval);
-	    RBASIC(newprocval)->klass = klass;
+	    RBASIC_SET_CLASS(newprocval, klass);
 	    return newprocval;
 	}
     }