diff --git a/unix/fdset_test.go b/unix/fdset_test.go
index e092785c..d0c2d8a7 100644
--- a/unix/fdset_test.go
+++ b/unix/fdset_test.go
@@ -50,4 +50,14 @@ func TestFdSet(t *testing.T) {
 			}
 		}
 	}
+
+	for fd := 1; fd < unix.FD_SETSIZE; fd += 2 {
+		fdSet.Clear(fd)
+	}
+
+	for fd := 0; fd < unix.FD_SETSIZE; fd++ {
+		if fdSet.IsSet(fd) {
+			t.Fatalf("Clear(%d) did not clear fd", fd)
+		}
+	}
 }