diff --git a/src/iperf_api.c b/src/iperf_api.c
index f56d775..55660c9 100644
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -390,7 +390,7 @@ iperf_has_zerocopy( void )
 void
 iperf_set_test_zerocopy(struct iperf_test *ipt, int zerocopy)
 {
-    ipt->zerocopy = zerocopy;
+    ipt->zerocopy = (zerocopy && has_sendfile());
 }
 
 void