diff --git a/extensions/ql-vscode/src/common/vscode/file-path-discovery.ts b/extensions/ql-vscode/src/common/vscode/file-path-discovery.ts
index 47b37f9ff..4e3e53b7f 100644
--- a/extensions/ql-vscode/src/common/vscode/file-path-discovery.ts
+++ b/extensions/ql-vscode/src/common/vscode/file-path-discovery.ts
@@ -33,7 +33,7 @@ interface PathData {
  */
 export abstract class FilePathDiscovery<T extends PathData> extends Discovery {
   /** The set of known paths and associated data that we are tracking */
-  protected pathData: T[] = [];
+  private pathData: T[] = [];
 
   /** Event that fires whenever the contents of `pathData` changes */
   protected readonly onDidChangePathDataEmitter: AppEventEmitter<void>;
@@ -71,6 +71,10 @@ export abstract class FilePathDiscovery<T extends PathData> extends Discovery {
     this.push(this.watcher.onDidChange(this.fileChanged.bind(this)));
   }
 
+  protected getPathData(): readonly T[] {
+    return this.pathData;
+  }
+
   /**
    * Compute any extra data to be stored regarding the given path.
    */
diff --git a/extensions/ql-vscode/src/queries-panel/query-discovery.ts b/extensions/ql-vscode/src/queries-panel/query-discovery.ts
index 3ff46bc8e..a813dab30 100644
--- a/extensions/ql-vscode/src/queries-panel/query-discovery.ts
+++ b/extensions/ql-vscode/src/queries-panel/query-discovery.ts
@@ -59,7 +59,7 @@ export class QueryDiscovery
   public buildQueryTree(): Array<FileTreeNode<string>> {
     const roots = [];
     for (const workspaceFolder of getOnDiskWorkspaceFoldersObjects()) {
-      const queriesInRoot = this.pathData.filter((query) =>
+      const queriesInRoot = this.getPathData().filter((query) =>
         containsPath(workspaceFolder.uri.fsPath, query.path),
       );
       if (queriesInRoot.length === 0) {
diff --git a/extensions/ql-vscode/src/queries-panel/query-pack-discovery.ts b/extensions/ql-vscode/src/queries-panel/query-pack-discovery.ts
index 495a6b801..88790091d 100644
--- a/extensions/ql-vscode/src/queries-panel/query-pack-discovery.ts
+++ b/extensions/ql-vscode/src/queries-panel/query-pack-discovery.ts
@@ -37,7 +37,7 @@ export class QueryPackDiscovery extends FilePathDiscovery<QueryPack> {
    */
   public getLanguageForQueryFile(queryPath: string): QueryLanguage | undefined {
     // Find all packs in a higher directory than the query
-    const packs = this.pathData.filter((queryPack) =>
+    const packs = this.getPathData().filter((queryPack) =>
       containsPath(dirname(queryPack.path), queryPath),
     );
 
diff --git a/extensions/ql-vscode/test/vscode-tests/minimal-workspace/common/vscode/file-path-discovery.test.ts b/extensions/ql-vscode/test/vscode-tests/minimal-workspace/common/vscode/file-path-discovery.test.ts
index 933b9124d..81666a771 100644
--- a/extensions/ql-vscode/test/vscode-tests/minimal-workspace/common/vscode/file-path-discovery.test.ts
+++ b/extensions/ql-vscode/test/vscode-tests/minimal-workspace/common/vscode/file-path-discovery.test.ts
@@ -28,8 +28,8 @@ class TestFilePathDiscovery extends FilePathDiscovery<TestData> {
     return this.onDidChangePathDataEmitter.event;
   }
 
-  public getPathData(): TestData[] {
-    return this.pathData;
+  public getPathData(): readonly TestData[] {
+    return super.getPathData();
   }
 
   protected async getDataForPath(path: string): Promise<TestData> {