diff --git a/src/tools/stringTools.cpp b/src/tools/stringTools.cpp
index f3d206e41..ef596f1e1 100644
--- a/src/tools/stringTools.cpp
+++ b/src/tools/stringTools.cpp
@@ -303,10 +303,10 @@ std::string kiwix::join(const std::vector<std::string>& list, const std::string&
   std::stringstream ss;
   bool first = true;
   for (auto& s:list) {
-    if (first) {
+    if (!first) {
       ss << sep;
-      first = false;
     }
+    first = false;
     ss << s;
   }
   return ss.str();
diff --git a/test/meson.build b/test/meson.build
index 2777d1ea5..437f5b528 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -4,7 +4,8 @@ tests = [
     'parseUrl',
     'library',
     'regex',
-    'tagParsing'
+    'tagParsing',
+    'stringTools'
 ]
 
 
diff --git a/test/stringTools.cpp b/test/stringTools.cpp
new file mode 100644
index 000000000..c632f0b7c
--- /dev/null
+++ b/test/stringTools.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 Matthieu Gautier
+ *
+ * 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 the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * is provided AS IS, WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, and
+ * NON-INFRINGEMENT.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ */
+
+#include "gtest/gtest.h"
+#include <string>
+#include <vector>
+
+namespace kiwix {
+std::string join(const std::vector<std::string>& list, const std::string& sep);
+};
+
+using namespace kiwix;
+#define parse_tag getTagValueFromTagList
+
+namespace
+{
+TEST(stringTools, join)
+{
+  std::vector<std::string> list = { "a", "b", "c" };
+  ASSERT_EQ(join(list, ";"), "a;b;c");
+}
+
+};
+int main(int argc, char** argv)
+{
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}