diff --git a/src/structs.h b/src/structs.h
index 5c606d8..4ae94fd 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1765,6 +1765,9 @@
     char_u	*(*eval_getline)(int, void *, int, int);
     void	*eval_cookie;	    // argument for eval_getline()
 
+    // used when compiling a :def function, NULL otherwise
+    cctx_T	*eval_cctx;
+
     // Used to collect lines while parsing them, so that they can be
     // concatenated later.  Used when "eval_ga.ga_itemsize" is not zero.
     // "eval_ga.ga_data" is a list of pointers to lines.