diff --git a/re.c b/re.c
index c75c5b3381..2d7ea2c4c3 100644
--- a/re.c
+++ b/re.c
@@ -2496,7 +2496,7 @@ static st_index_t reg_hash(VALUE re);
 static VALUE
 rb_reg_hash(VALUE re)
 {
-    st_index_t hashval;
+    st_index_t hashval = reg_hash(re);
     return LONG2FIX(hashval);
 }