diff --git a/ext/bert/c/decode.c b/ext/bert/c/decode.c
index 85c08e1..3e492f0 100644
--- a/ext/bert/c/decode.c
+++ b/ext/bert/c/decode.c
@@ -27,14 +27,9 @@ static VALUE rb_mBERT;
 static VALUE rb_cDecode;
 static VALUE rb_cTuple;
 
-typedef struct bert_buf bert_buf;
-
-typedef VALUE (*bert_ptr)(struct bert_buf *buf);
-
 struct bert_buf {
 	const uint8_t *data;
 	const uint8_t *end;
-	bert_ptr *callbacks;
 };
 
 static VALUE bert_read_invalid(struct bert_buf *buf);
@@ -51,10 +46,10 @@ static VALUE bert_read_list(struct bert_buf *buf);
 static VALUE bert_read_bin(struct bert_buf *buf);
 static VALUE bert_read_enc_string(struct bert_buf *buf);
 static VALUE bert_read_unicode_string(struct bert_buf *buf);
-static VALUE bert_read_unicode_string(struct bert_buf *buf);
 static VALUE bert_read_sbignum(struct bert_buf *buf);
 static VALUE bert_read_lbignum(struct bert_buf *buf);
 
+typedef VALUE (*bert_ptr)(struct bert_buf *buf);
 static bert_ptr bert_callbacks[] = {
 	&bert_read_sint,
 	&bert_read_int,
@@ -118,7 +113,7 @@ static VALUE bert_read(struct bert_buf *buf)
 	if (!BERT_VALID_TYPE(type))
 		rb_raise(rb_eRuntimeError, "Invalid tag '%d' for term", type);
 
-	return buf->callbacks[type - BERT_TYPE_OFFSET](buf);
+	return bert_callbacks[type - BERT_TYPE_OFFSET](buf);
 }
 
 static VALUE bert_read_dict(struct bert_buf *buf)
@@ -517,17 +512,11 @@ static VALUE rb_bert_decode(VALUE klass, VALUE rb_string)
 	bert_buf_ensure(&buf, 1);
 
 	proto_version = bert_buf_read8(&buf);
-	switch(proto_version) {
-	    case ERL_VERSION:
-		buf.callbacks = bert_callbacks;
-		break;
-	    case ERL_VERSION2:
-		buf.callbacks = bert_callbacks;
-		break;
-	    default:
-		rb_raise(rb_eTypeError, "Invalid magic value for BERT string");
+	if (proto_version == ERL_VERSION || proto_version == ERL_VERSION2) {
+	    return bert_read(&buf);
+	} else {
+	    rb_raise(rb_eTypeError, "Invalid magic value for BERT string");
 	}
-	return bert_read(&buf);
 }
 
 static VALUE rb_bert_impl(VALUE klass)