diff --git a/script/test b/script/test
index a1c86185..be789814 100755
--- a/script/test
+++ b/script/test
@@ -1,6 +1,13 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+# Silence git's "default branch name" hints emitted on every `git init` in
+# tests that create temp repos. Sets init.defaultBranch=master via env so we
+# don't have to touch the user's real git config.
+export GIT_CONFIG_COUNT=1
+export GIT_CONFIG_KEY_0=init.defaultBranch
+export GIT_CONFIG_VALUE_0=master
+
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"