diff --git a/lib/index/meson.build b/lib/index/meson.build
index 237adf62..5da34fce 100644
--- a/lib/index/meson.build
+++ b/lib/index/meson.build
@@ -1,4 +1,4 @@
-## Copyright (C) 2021 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+## Copyright (C) 2021-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ##
 ## This program is free software; you can redistribute it and/or modify
 ## it under the terms of the GNU General Public License as published by
@@ -36,3 +36,14 @@ lib_mu_index=static_library('mu-index', [index_srcs],
 lib_mu_index_dep = declare_dependency(
   link_with: lib_mu_index
 )
+
+#
+# tests
+#
+
+test('test-scanner',
+     executable('test-scanner', 'mu-scanner.cc',
+                install: false,
+                cpp_args: ['-DBUILD_TESTS'],
+                dependencies: [glib_dep, config_h_dep,
+                               lib_mu_utils_dep]))
diff --git a/lib/index/mu-scanner.cc b/lib/index/mu-scanner.cc
index 5072eb9b..0b8aee80 100644
--- a/lib/index/mu-scanner.cc
+++ b/lib/index/mu-scanner.cc
@@ -134,7 +134,15 @@ Scanner::Private::process_dir(const std::string& path, bool is_maildir)
 	if (!running_)
 		return true; /* we're done */
 
-	const auto dir = opendir(path.c_str());
+	if (G_UNLIKELY(path.length() > PATH_MAX)) {
+		// note: unlikely to hit this, one case would be a
+		// self-referential symlink; that should be caught earlier,
+		// so this is just a backstop.
+		mu_warning("path is too long: {}", path);
+		return false;
+	}
+
+	const auto dir{::opendir(path.c_str())};
 	if (G_UNLIKELY(!dir)) {
 		mu_warning("failed to scan dir {}: {}", path, g_strerror(errno));
 		return false;
@@ -145,7 +153,7 @@ Scanner::Private::process_dir(const std::string& path, bool is_maildir)
 
 	while (running_) {
 		errno = 0;
-		const auto dentry{readdir(dir)};
+		const auto dentry{::readdir(dir)};
 
 		if (G_LIKELY(dentry)) {
 			process_dentry(path, dentry, is_maildir);
@@ -169,7 +177,7 @@ Scanner::Private::start()
 {
 	const auto& path{root_dir_};
 	if (G_UNLIKELY(path.length() > PATH_MAX)) {
-		mu_warning("path too long");
+		mu_warning("path is too long: {}", path);
 		return false;
 	}
 
@@ -251,3 +259,51 @@ Scanner::is_running() const
 {
 	return priv_->running_;
 }
+
+
+
+
+#if BUILD_TESTS
+#include "mu-test-utils.hh"
+
+
+static void
+test_scan_maildir()
+{
+	allow_warnings();
+
+	size_t count{};
+	Scanner scanner{
+		MU_TESTMAILDIR,
+		[&](const std::string& fullpath, const struct stat* statbuf, auto&& htype) -> bool {
+			mu_debug("{} {}", fullpath, statbuf->st_size);
+			++count;
+			return true;
+		}};
+	g_assert_true(scanner.start());
+
+	while (scanner.is_running()) { g_usleep(1000); }
+
+	// very rudimentary test...
+	g_assert_cmpuint(count,==,23);
+}
+
+int
+main(int argc, char* argv[])
+try {
+	g_test_init(&argc, &argv, NULL);
+
+	g_test_add_func("/index/scanner/scan-maildir", test_scan_maildir);
+
+	return g_test_run();
+
+} catch (const std::runtime_error& re) {
+	mu_printerrln("caught runtime error: {}", re.what());
+	return 1;
+} catch (...) {
+	mu_printerrln("caught exception");
+	return 1;
+}
+
+
+#endif /*BUILD_TESTS*/
diff --git a/lib/index/test-scanner.cc b/lib/index/test-scanner.cc
deleted file mode 100644
index 4835aa13..00000000
--- a/lib/index/test-scanner.cc
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
-** Copyright (C) 2017 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
-**
-**  This library is free software; you can redistribute it and/or
-**  modify it under the terms of the GNU Lesser General Public License
-**  as published by the Free Software Foundation; either version 2.1
-**  of the License, or (at your option) any later version.
-**
-**  This library is distributed in the hope that it will be useful,
-**  but WITHOUT ANY WARRANTY; without even the implied warranty of
-**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-**  Lesser General Public License for more details.
-**
-**  You should have received a copy of the GNU Lesser General Public
-**  License along with this library; if not, write to the Free
-**  Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-**  02110-1301, USA.
-*/
-
-#include <vector>
-#include <glib.h>
-
-#include <iostream>
-#include <sstream>
-
-#include "mu-scanner.hh"
-#include "mu-utils.hh"
-
-using namespace Mu;
-
-static void
-test_scan_maildir()
-{
-	allow_warnings();
-
-	Scanner scanner{
-	    "/home/djcb/Maildir",
-	    [](const dirent* dentry) -> bool {
-		    g_print("%02x %s\n", dentry->d_type, dentry->d_name);
-		    return true;
-	    },
-	    [](const std::string& fullpath, const struct stat* statbuf, auto&& info) -> bool {
-		    g_print("%s %zu\n", fullpath.c_str(), statbuf->st_size);
-		    return true;
-	    }};
-	g_assert_true(scanner.start());
-
-	while (scanner.is_running()) {
-		sleep(1);
-	}
-}
-
-int
-main(int argc, char* argv[])
-try {
-	g_test_init(&argc, &argv, NULL);
-
-	g_test_add_func("/utils/scanner/scan-maildir", test_scan_maildir);
-
-	return g_test_run();
-
-} catch (const std::runtime_error& re) {
-	std::cerr << re.what() << "\n";
-	return 1;
-}