diff --git a/src/structs.h b/src/structs.h
index bdc763b..4a0c10a 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1539,6 +1539,7 @@
 typedef enum {
     UF_NOT_COMPILED,
     UF_TO_BE_COMPILED,
+    UF_COMPILING,
     UF_COMPILED
 } def_status_T;