diff --git a/examples/nettle-benchmark.c b/examples/nettle-benchmark.c
index 5d0e649e..2808f70d 100644
--- a/examples/nettle-benchmark.c
+++ b/examples/nettle-benchmark.c
@@ -152,9 +152,11 @@ time_function(void (*f)(void *arg), void *arg)
   return elapsed / ncalls - overhead;
 }
 
+volatile int unused = 0;
 static void
 bench_nothing(void *arg UNUSED)
 {
+  unused = 1;
   return;
 }