diff --git a/src/crypto/asn1.c b/src/crypto/asn1.c
index ff56e1f3..549ee4d8 100644
--- a/src/crypto/asn1.c
+++ b/src/crypto/asn1.c
@@ -739,7 +739,7 @@ static size_t asn1_header ( struct asn1_builder_header *header,
  * @v extra		Extra space to prepend
  * @ret rc		Return status code
  */
-static int asn1_grow ( struct asn1_builder *builder, size_t extra ) {
+int asn1_grow ( struct asn1_builder *builder, size_t extra ) {
 	size_t new_len;
 	void *new;
 
diff --git a/src/include/ipxe/asn1.h b/src/include/ipxe/asn1.h
index b0a82c00..5a6c0d9c 100644
--- a/src/include/ipxe/asn1.h
+++ b/src/include/ipxe/asn1.h
@@ -365,6 +365,7 @@ extern int asn1_signature_algorithm ( const struct asn1_cursor *cursor,
 				      struct asn1_algorithm **algorithm );
 extern int asn1_generalized_time ( const struct asn1_cursor *cursor,
 				   time_t *time );
+extern int asn1_grow ( struct asn1_builder *builder, size_t extra );
 extern int asn1_prepend_raw ( struct asn1_builder *builder, const void *data,
 			      size_t len );
 extern int asn1_prepend ( struct asn1_builder *builder, unsigned int type,