diff --git a/include/boost/static_string/config.hpp b/include/boost/static_string/config.hpp
index 7d681ba..489297c 100644
--- a/include/boost/static_string/config.hpp
+++ b/include/boost/static_string/config.hpp
@@ -60,7 +60,6 @@
 #define BOOST_STATIC_STRING_NODISCARD
 #endif
 
-
 // MSVC doesn't define __cplusplus by default
 #ifdef _MSVC_LANG
 #define BOOST_STATIC_STRING_STANDARD_VERSION _MSVC_LANG
@@ -168,12 +167,9 @@ defined(__clang__) && \
 // that cannot use the library comparison function
 // objects at all in constant expresssions. In these
 // cases, we use whatever will make more constexpr work.
-#if defined(__clang__) 
-#if defined(__GLIBCXX__) && ((__GLIBCXX__ > 20181206 && __GLIBCXX__ <= 20190812))
+#if defined(__clang__) && defined(__GLIBCXX__) && \
+((__GLIBCXX__ >= 20180726 && __GLIBCXX__ <= 20190812))
 #define BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS
-#elif BOOST_STATIC_STRING_HAS_BUILTIN(__builtin_constant_p) || defined(BOOST_STATIC_STRING_IS_CONST_EVAL)
-#define BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS
-#endif
 #endif
 
 namespace boost {
diff --git a/include/boost/static_string/static_string.hpp b/include/boost/static_string/static_string.hpp
index 6711049..c1724e3 100644
--- a/include/boost/static_string/static_string.hpp
+++ b/include/boost/static_string/static_string.hpp
@@ -627,15 +627,6 @@ is_inside(
         return true;
     return false;
   }
-#elif defined(__clang__) && BOOST_STATIC_STRING_HAS_BUILTIN(__builtin_constant_p)
-  // We can also try using __builtin_constant_p
-  if (__builtin_constant_p((ptr, src_first, src_last)))
-  {
-    for (; src_first != src_last; ++src_first)
-      if (src_first == ptr)
-        return true;
-    return false;
-  }
 #else
   // If library comparison functions don't work, and
   // we cannot use any of the above, we can use