diff --git a/lib/asn1/der.h b/lib/asn1/der.h
index cef92aa07..3243fbe32 100644
--- a/lib/asn1/der.h
+++ b/lib/asn1/der.h
@@ -94,6 +94,12 @@ typedef struct heim_ber_time_t {
     int bt_zone;
 } heim_ber_time_t;
 
+struct heim_acode {
+    size_t size;
+    unsigned int op;
+    void *arg1;
+};
+
 #include <der-protos.h>
 
 int _heim_fix_dce(size_t reallen, size_t *len);