diff --git a/includes/Checker/Abstract_Check_Runner.php b/includes/Checker/Abstract_Check_Runner.php
index b52db568f..8cb612c5b 100644
--- a/includes/Checker/Abstract_Check_Runner.php
+++ b/includes/Checker/Abstract_Check_Runner.php
@@ -8,9 +8,9 @@
 namespace WordPress\Plugin_Check\Checker;
 
 use Exception;
+use WordPress\Plugin_Check\Checker\Exception\Invalid_Check_Slug_Exception;
 use WordPress\Plugin_Check\Checker\Preparations\Universal_Runtime_Preparation;
 use WordPress\Plugin_Check\Utilities\Plugin_Request_Utility;
-use WP_CLI;
 
 /**
  * Abstract Check Runner class.
@@ -294,17 +294,31 @@ final public function set_categories( $categories ) {
 	final public function prepare() {
 		$cleanup_functions = array();
 
-		try {
-			if ( $this->has_runtime_check( $this->get_checks_to_run() ) ) {
-				$preparation         = new Universal_Runtime_Preparation( $this->get_check_context() );
-				$cleanup_functions[] = $preparation->prepare();
-			}
-		} catch ( Exception $error ) {
-			if ( defined( 'WP_CLI' ) && WP_CLI ) {
-				WP_CLI::error( $error->getMessage() );
-			} else {
-				throw $error;
+		if ( $this->initialized_early ) {
+			/*
+			 * When initialized early, plugins are not loaded yet when this method is called.
+			 * Therefore it could be that check slugs provided refer to addon checks that are not loaded yet.
+			 * In that case, the only reliable option is to assume that it refers to an addon check and that the addon
+			 * check is a runtime check. We don't know, but better to have the runtime preparations initialize
+			 * unnecessarily rather than not having them when needed.
+			 *
+			 * The actual checks to run are retrieved later (once plugins are loaded), so if one of the provided slugs
+			 * is actually invalid, the exception will still be thrown at that point.
+			 */
+			try {
+				$checks             = $this->get_checks_to_run();
+				$initialize_runtime = $this->has_runtime_check( $checks );
+			} catch ( Invalid_Check_Slug_Exception $e ) {
+				$initialize_runtime = true;
 			}
+		} else {
+			// When not initialized early, all checks are loaded, so we can simply see if there are runtime checks.
+			$initialize_runtime = $this->has_runtime_check( $this->get_checks_to_run() );
+		}
+
+		if ( $initialize_runtime ) {
+			$preparation         = new Universal_Runtime_Preparation( $this->get_check_context() );
+			$cleanup_functions[] = $preparation->prepare();
 		}
 
 		if ( $this->delete_plugin_folder ) {
diff --git a/includes/Checker/Check_Collection.php b/includes/Checker/Check_Collection.php
index d6fb8290b..e86d0517e 100644
--- a/includes/Checker/Check_Collection.php
+++ b/includes/Checker/Check_Collection.php
@@ -9,8 +9,8 @@
 
 use ArrayAccess;
 use Countable;
-use Exception;
 use IteratorAggregate;
+use WordPress\Plugin_Check\Checker\Exception\Invalid_Check_Slug_Exception;
 
 /**
  * Check Collection interface.
@@ -82,7 +82,7 @@ public function exclude( array $check_slugs ): Check_Collection;
 	 * @param array $check_slugs List of slugs to limit to only those. If empty, the same collection is returned.
 	 * @return Check_Collection The unchanged check collection.
 	 *
-	 * @throws Exception Thrown when any of the given check slugs is not present in the collection.
+	 * @throws Invalid_Check_Slug_Exception Thrown when any of the given check slugs is not present in the collection.
 	 */
 	public function require( array $check_slugs ): Check_Collection;
 }
diff --git a/includes/Checker/Default_Check_Collection.php b/includes/Checker/Default_Check_Collection.php
index e135b61d7..a21ede83b 100644
--- a/includes/Checker/Default_Check_Collection.php
+++ b/includes/Checker/Default_Check_Collection.php
@@ -8,8 +8,8 @@
 namespace WordPress\Plugin_Check\Checker;
 
 use ArrayIterator;
-use Exception;
 use Traversable;
+use WordPress\Plugin_Check\Checker\Exception\Invalid_Check_Slug_Exception;
 
 /**
  * Default Check Collection class.
@@ -150,12 +150,12 @@ static function ( Check $check, $slug ) use ( $check_slugs ) {
 	 * @param array $check_slugs List of slugs to limit to only those. If empty, the same collection is returned.
 	 * @return Check_Collection The unchanged check collection.
 	 *
-	 * @throws Exception Thrown when any of the given check slugs is not present in the collection.
+	 * @throws Invalid_Check_Slug_Exception Thrown when any of the given check slugs is not present in the collection.
 	 */
 	public function require( array $check_slugs ): Check_Collection {
 		foreach ( $check_slugs as $slug ) {
 			if ( ! isset( $this->checks[ $slug ] ) ) {
-				throw new Exception(
+				throw new Invalid_Check_Slug_Exception(
 					sprintf(
 						/* translators: %s: The Check slug. */
 						__( 'Check with the slug "%s" does not exist.', 'plugin-check' ),
diff --git a/includes/Checker/Exception/Invalid_Check_Slug_Exception.php b/includes/Checker/Exception/Invalid_Check_Slug_Exception.php
new file mode 100644
index 000000000..cd1144f5f
--- /dev/null
+++ b/includes/Checker/Exception/Invalid_Check_Slug_Exception.php
@@ -0,0 +1,19 @@
+<?php
+/**
+ * Class WordPress\Plugin_Check\Checker\Exception\Invalid_Check_Slug_Exception
+ *
+ * @package plugin-check
+ */
+
+namespace WordPress\Plugin_Check\Checker\Exception;
+
+use InvalidArgumentException;
+
+/**
+ * Class for an exception thrown when an invalid check slug is provided.
+ *
+ * @since n.e.x.t
+ */
+class Invalid_Check_Slug_Exception extends InvalidArgumentException {
+
+}
diff --git a/tests/behat/features/plugin-check.feature b/tests/behat/features/plugin-check.feature
index b4db039fc..a50e841d1 100644
--- a/tests/behat/features/plugin-check.feature
+++ b/tests/behat/features/plugin-check.feature
@@ -514,10 +514,18 @@ Feature: Test that the WP-CLI command works.
       WordPress.WP.EnqueuedResourceParameters.NotInFooter,WARNING
       """
 
-# This doesn't currently work, because we are not actually loading any other plugins, including pcp-addon.
+    # This doesn't currently work, because we are not actually loading any other plugins, including pcp-addon.
 #    And STDOUT should contain:
 #      """
 #      ExampleRuntimeCheck.ForbiddenScript,WARNING
+#      """
+
+    # This doesn't currently work.
+    # Run one runtime check from PCP and one from pcp-addon.
+#    When I run the WP-CLI command `plugin check foo-sample --checks=non_blocking_scripts,example_runtime --fields=code,type --format=csv --require=./wp-content/plugins/plugin-check/cli.php`
+#    Then STDOUT should contain:
+#      """
+#      ExampleRuntimeCheck.ForbiddenScript,WARNING
 #      """
 
     # This doesn't currently work, because we are not actually loading any other plugins, including pcp-addon.