1 files changed, 5 insertions, 0 deletions
diff --git a/re.c b/re.c
index 3a2aa5d362..a45ae47d9f 100644
--- a/re.c
+++ b/re.c
@@ -2312,6 +2312,11 @@ rb_reg_initialize(VALUE obj, const char *s, int len, rb_encoding *enc,
         rb_raise(rb_eTypeError, "already initialized regexp");
     re->ptr = 0;
 
+    if (rb_enc_dummy_p(enc)) {
+	    strcpy(err, "can't make regexp with dummy encoding");
+	    return -1;
+    }
+
     unescaped = rb_reg_preprocess(s, s+len, enc, &fixed_enc, err);
     if (unescaped == Qnil)
         return -1;