diff --git a/src/os/env_test.go b/src/os/env_test.go
index e5749f0..16f1945 100644
--- a/src/os/env_test.go
+++ b/src/os/env_test.go
@@ -134,7 +134,7 @@
 	if err != nil {
 		t.Fatalf("failed to release smallpox virus")
 	}
-	value, ok = LookupEnv(smallpox)
+	_, ok = LookupEnv(smallpox)
 	if !ok {
 		t.Errorf("smallpox release failed; world remains safe but LookupEnv is broken")
 	}