diff --git a/include/cereal/archives/xml.hpp b/include/cereal/archives/xml.hpp
index 575c11c9c..d04cf6afa 100644
--- a/include/cereal/archives/xml.hpp
+++ b/include/cereal/archives/xml.hpp
@@ -233,9 +233,12 @@ namespace cereal
         itsOS << value << std::ends;
 
         const auto strValue = itsOS.str();
-        // if there is the first or the last character in string is whitespace then add xml:space attribute
-        // the last character has index length-2 because there is \0 character at end added with std::ends
-        if( !strValue.empty() && ( xml_detail::isWhitespace( strValue[0] ) || xml_detail::isWhitespace( strValue[strValue.length() - 2] ) ) )
+
+        // If the first or last character is a whitespace, add xml:space attribute
+        // the string always contains a '\0' added by std::ends, so the last character is at len-2 and an 'empty' 
+        // string has a length of 1 or lower
+        const auto len = strValue.length();
+        if ( len > 1 && ( xml_detail::isWhitespace( strValue[0] ) || xml_detail::isWhitespace( strValue[len - 2] ) ) )
         {
           itsNodes.top().node->append_attribute( itsXML.allocate_attribute( "xml:space", "preserve" ) );
         }
diff --git a/unittests/basic_string.cpp b/unittests/basic_string.cpp
index ea523e50a..ede18525c 100644
--- a/unittests/basic_string.cpp
+++ b/unittests/basic_string.cpp
@@ -38,16 +38,19 @@ void test_string_basic()
   {
     std::basic_string<char> o_string  = random_basic_string<char>(gen);
     std::basic_string<char> o_string2 = "";
+    std::basic_string<char> o_string3;
 
     std::ostringstream os;
     {
       OArchive oar(os);
       oar(o_string);
       oar(o_string2);
+      oar(o_string3);
     }
 
     std::basic_string<char> i_string;
     std::basic_string<char> i_string2;
+    std::basic_string<char> i_string3;
 
     std::istringstream is(os.str());
     {
@@ -55,10 +58,12 @@ void test_string_basic()
 
       iar(i_string);
       iar(i_string2);
+      iar(i_string3);
     }
 
     BOOST_CHECK_EQUAL(i_string, o_string);
     BOOST_CHECK_EQUAL(i_string2, o_string2);
+    BOOST_CHECK_EQUAL(i_string3, o_string3);
   }
 }
 
@@ -148,7 +153,6 @@ void test_ws_in_out(Out const & o_value_with_ws)
 
 namespace boost
 {
-
   void save( cereal::XMLOutputArchive & ar, boost::string_ref const & str )
   {
     ar.saveValue( str );