Index: boost/property_tree/detail/ptree_utils.hpp
===================================================================
--- boost/property_tree/detail/ptree_utils.hpp	(revision 82806)
+++ boost/property_tree/detail/ptree_utils.hpp	(working copy)
@@ -66,6 +66,21 @@
         return result;
     }
 
+    // Helper to avoid gcc comparison-always-false (-Wtype-limits) warning
+    template<class Ch>
+    typename std::enable_if<std::is_unsigned<Ch>::value, bool>::type
+    value_outside_narrow(const Ch& ch)
+    {
+        return ch > (std::numeric_limits<char>::max)();
+    }
+
+    template<class Ch>
+    typename std::enable_if<!std::is_unsigned<Ch>::value, bool>::type
+    value_outside_narrow(const Ch& ch)
+    {
+        return ch < 0 || ch > (std::numeric_limits<char>::max)();
+    }
+
     // Naively convert string to narrow character type
     template<class Ch>
     std::string narrow(const Ch *text)
@@ -73,7 +88,7 @@
         std::string result;
         while (*text)
         {
-            if (*text < 0 || *text > (std::numeric_limits<char>::max)())
+            if (value_outside_narrow(*text))
                 result += '*';
             else
                 result += char(*text);