diff --git a/src/userfunc.c b/src/userfunc.c
index 67d9c6d..ea15423 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -58,9 +58,8 @@
 #define FC_DICT	    4		/* Dict function, uses "self" */
 
 /* From user function to hashitem and back. */
-static ufunc_T dumuf;
 #define UF2HIKEY(fp) ((fp)->uf_name)
-#define HIKEY2UF(p)  ((ufunc_T *)(p - (dumuf.uf_name - (char_u *)&dumuf)))
+#define HIKEY2UF(p)  ((ufunc_T *)(p - offsetof(ufunc_T, uf_name)))
 #define HI2UF(hi)     HIKEY2UF((hi)->hi_key)
 
 #define FUNCARG(fp, j)	((char_u **)(fp->uf_args.ga_data))[j]