diff --git a/tesseract/genconf/env.go b/tesseract/genconf/env.go
index ca061a4..e53a34b 100644
--- a/tesseract/genconf/env.go
+++ b/tesseract/genconf/env.go
@@ -40,6 +40,7 @@ func generateEnv(yamlFile string, wantDiff bool, allowWrite bool, useColor bool)
 			"--batch_max_age=2000ms",
 			"--pushback_max_outstanding=4096",
 			"--rate_limit_dedup=500",
+			"--ext_key_usages=ServerAuth",
 		}
 
 		// Add http_endpoint if Listen is specified