diff --git a/README.md b/README.md
index ceb0c980..485e0b0d 100644
--- a/README.md
+++ b/README.md
@@ -147,6 +147,15 @@ chmod +x ~/wp-cli/wp
 WP_CLI_BIN_DIR=~/wp-cli composer behat
 ```
 
+#### Project configuration trust
+
+WP-CLI asks for confirmation before acting on `require`, `exec`, `env` or `ssh-args` directives found in a project-level `wp-cli.yml` file. Test fixtures create such files all the time and a test run cannot answer an interactive prompt, so the Behat context passes `WP_CLI_TRUST_PROJECT_CONFIG=1` to every command it runs.
+
+Set the `WP_CLI_TRUST_PROJECT_CONFIG` environment variable yourself to override that default for the whole run. Individual scenarios can override it per command:
+```
+When I try `WP_CLI_TRUST_PROJECT_CONFIG=false wp cli version`
+```
+
 ### Setting up the tests in Travis CI
 
 Basic rules for setting up the test framework with Travis CI:
diff --git a/src/Context/FeatureContext.php b/src/Context/FeatureContext.php
index 867f535c..c4055ad7 100644
--- a/src/Context/FeatureContext.php
+++ b/src/Context/FeatureContext.php
@@ -489,6 +489,14 @@ private static function get_process_env_variables(): array {
 			$env['WP_CLI_REQUIRE'] = $updated;
 		}
 
+		// Test fixtures routinely create project-level `wp-cli.yml` files that contain
+		// `require`, `exec`, `env` or `ssh-args` directives. WP-CLI gates those behind a
+		// trust confirmation, which cannot be answered in a non-interactive test run, so
+		// trust them by default. Scenarios that specifically test the trust mechanism can
+		// still override this by prefixing their command with their own value.
+		$trust_project_config               = getenv( 'WP_CLI_TRUST_PROJECT_CONFIG' );
+		$env['WP_CLI_TRUST_PROJECT_CONFIG'] = false !== $trust_project_config ? $trust_project_config : '1';
+
 		$config_path = getenv( 'WP_CLI_CONFIG_PATH' );
 		if ( false !== $config_path ) {
 			$env['WP_CLI_CONFIG_PATH'] = $config_path;