diff --git a/packages/cli-node/api-report.md b/packages/cli-node/api-report.md
index a16b4c91a4..9f7e525048 100644
--- a/packages/cli-node/api-report.md
+++ b/packages/cli-node/api-report.md
@@ -18,7 +18,7 @@ export interface BackstagePackageJson {
   backstage?: {
     role?: PackageRole;
     moved?: string;
-    pluginId?: string;
+    pluginId?: string | null;
     pluginPackage?: string;
     pluginPackages?: string[];
   };
diff --git a/packages/cli-node/src/monorepo/PackageGraph.ts b/packages/cli-node/src/monorepo/PackageGraph.ts
index 027099fe40..c8877803d5 100644
--- a/packages/cli-node/src/monorepo/PackageGraph.ts
+++ b/packages/cli-node/src/monorepo/PackageGraph.ts
@@ -48,7 +48,7 @@ export interface BackstagePackageJson {
     moved?: string;
 
     /**
-     * The ID of the plugin if this is a plugin package. Must always be set for plugin and module packages, and may be set for library packages.
+     * The ID of the plugin if this is a plugin package. Must always be set for plugin and module packages, and may be set for library packages. A `null` value means that the package is explicitly not a plugin package.
      */
     pluginId?: string | null;