diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index 95c8b5d..199183e 100755
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -1236,7 +1236,7 @@
         test_env_vars.append("BAZELISK_USER_AGENT")
 
         # Avoid "Network is unreachable" errors in IPv6-only environments
-        for e in ("JAVA_TOOL_OPTIONS", "SSL_CERT_FILE"):
+        for e in ("COURSIER_OPTS", "JAVA_TOOL_OPTIONS", "SSL_CERT_FILE"):
             if os.getenv(e):
                 test_env_vars.append(e)