diff --git a/src/main/cpp/blaze_startup_options.cc b/src/main/cpp/blaze_startup_options.cc
index 569c561e7b0cc7..ffbe403154ed45 100644
--- a/src/main/cpp/blaze_startup_options.cc
+++ b/src/main/cpp/blaze_startup_options.cc
@@ -91,7 +91,10 @@ string BlazeStartupOptions::GetWorkspace(const string &cwd) {
     }
     workspace = blaze_util::Dirname(workspace);
   } while (!workspace.empty() && workspace != "/");
-  return "";
+
+  fprintf(stderr, "Could not find WORKSPACE file at or above %s.\n"
+          "Is your current directory in a Bazel source tree?\n", cwd.c_str());
+  exit(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR);
 }
 
 blaze_exit_code::ExitCode BlazeStartupOptions::ProcessArgExtra(