diff --git a/src/contributions/commands/isURI.ts b/src/contributions/commands/isURI.ts
new file mode 100644
index 0000000..ec223ce
--- /dev/null
+++ b/src/contributions/commands/isURI.ts
@@ -0,0 +1,10 @@
+import { URL } from "node:url";
+
+export function isURI(something: any): boolean {
+  try {
+    new URL(something);
+    return true;
+  } catch (error) {
+    return false;
+  }
+}
diff --git a/src/contributions/commands/workspace.ts b/src/contributions/commands/workspace.ts
index 1ed2b9d..3cb5fa4 100644
--- a/src/contributions/commands/workspace.ts
+++ b/src/contributions/commands/workspace.ts
@@ -4,9 +4,13 @@ import { runBuild } from "#building/build-runner";
 import * as stbls from "#stbls/stbl-commands";
 import { convertFolderToProject } from "#workspace/folder-to-project";
 import S4TKWorkspaceManager from "#workspace/workspace-manager";
+import { isURI } from "./isURI";
 
 export default function registerWorkspaceCommands() {
   vscode.commands.registerCommand(S4TKCommand.workspace.build, async (uri?: vscode.Uri) => {
+    if (!isURI(uri)) {
+      uri = undefined;
+    }
     const workspace = await S4TKWorkspaceManager.chooseWorkspace(uri);
     if (workspace) runBuild(workspace, "build", "Build");
   });