diff --git a/.travis.yml b/.travis.yml
index 091babd..2358ac7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -234,14 +234,14 @@ jobs:
         - ci/travis/coverity.sh
         
     # Standalone tests for StaticString
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-7",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *gcc-7     }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-8",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *gcc-8     }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-9",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *gcc-9     }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-6.0",   "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *clang-6   }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-7",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *clang-7   }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-8",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *clang-8   }
-    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-9",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ], addons: *clang-9   }
-    - { os: "osx"  , env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"    ]                     }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-7",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *gcc-7     }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-8",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *gcc-8     }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=gcc-9",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *gcc-9     }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-6.0",   "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *clang-6   }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-7",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *clang-7   }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-8",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"                                   ], addons: *clang-8   }
+    - { os: "linux", env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang-9",     "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17",    "B2_CXXFLAGS=-stdlib=libc++"]  , addons: *clang-9   }
+    - { os: "osx"  , env: [ "COMMENT=STANDALONE",       "B2_TOOLSET=clang",       "B2_DEFINES=define=BOOST_STATIC_STRING_STANDALONE",       "B2_CXXSTD=17"     ]                     }
         
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diff --git a/include/boost/static_string/config.hpp b/include/boost/static_string/config.hpp
index 489297c..ed4cfb5 100644
--- a/include/boost/static_string/config.hpp
+++ b/include/boost/static_string/config.hpp
@@ -168,7 +168,7 @@ defined(__clang__) && \
 // objects at all in constant expresssions. In these
 // cases, we use whatever will make more constexpr work.
 #if defined(__clang__) && defined(__GLIBCXX__) && \
-((__GLIBCXX__ >= 20180726 && __GLIBCXX__ <= 20190812))
+(__GLIBCXX__ >= 20180726 && __GLIBCXX__ <= 20190812)
 #define BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS
 #endif
 
@@ -185,5 +185,4 @@ using basic_string_view =
 #endif
 } // static_string
 } // boost
-
-#endif
+#endif
\ No newline at end of file
diff --git a/include/boost/static_string/static_string.hpp b/include/boost/static_string/static_string.hpp
index c1724e3..59feb98 100644
--- a/include/boost/static_string/static_string.hpp
+++ b/include/boost/static_string/static_string.hpp
@@ -614,8 +614,7 @@ is_inside(
   // of conformance, we will settle for the best option that is available.
   // We don't care about this in C++11, since this function would have
   // no applications in constant expressions.
-#ifdef BOOST_STATIC_STRING_CPP14
-#ifdef BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS 
+#if defined(BOOST_STATIC_STRING_CPP14) && defined(BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS) 
 #ifdef BOOST_STATIC_STRING_IS_CONST_EVAL
   // Our second best option is to use is_constant_evaluated
   // and a loop that checks for equality, since equality for 
@@ -633,7 +632,6 @@ is_inside(
   // try builtin comparison operators instead.
   return ptr >= src_first && ptr < src_last;
 #endif
-#endif
 #endif
   // Use the library comparison functions if we can't use 
   // is_constant_evaluated or if we don't need to.