diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 1e16bd9..77c7870 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -6838,7 +6838,7 @@
 nfa_regtry(prog, col, tm)
     nfa_regprog_T   *prog;
     colnr_T	    col;
-    proftime_T	    *tm;	/* timeout limit or NULL */
+    proftime_T	    *tm UNUSED;	/* timeout limit or NULL */
 {
     int		i;
     regsubs_T	subs, m;