diff --git a/configure.ac b/configure.ac
index 54f9f71bd..8d764d3a0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,12 +43,12 @@ AC_DEFUN([CHECK_COMPILER_BUILTIN],
     AC_MSG_RESULT(AS_VAR_GET([[have_]$1]))
     AS_IF([test yes = AS_VAR_GET([[have_]$1])],
         [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_]$1), 1,
-            [Define to 1 if the system has the `]$1[' built-in function])], []
+            [Define to 1 if the system has the `]$1[' built-in function])],
+            [AC_MSG_ERROR([`]$1[' is required, giving up.])]
         )])
 
 CHECK_COMPILER_BUILTIN([__builtin_unreachable],[]);
 
-
 dnl ##
 dnl ## Locate the GAP root dir
 dnl ##
diff --git a/gapbind14/include/gapbind14/cpp_fn.hpp b/gapbind14/include/gapbind14/cpp_fn.hpp
index a4e05f4ed..6123170a7 100644
--- a/gapbind14/include/gapbind14/cpp_fn.hpp
+++ b/gapbind14/include/gapbind14/cpp_fn.hpp
@@ -24,8 +24,7 @@
 #include <tuple>        // for tuple, tuple_element_t
 #include <type_traits>  // for true_type
 
-#include "../../../src/semigroups-config.hpp"  // for SEMIGRUOPS_HAVE___BUILTIN_UNREACHABLE
-#include "gap_include.hpp"                     // for UInt
+#include "gap_include.hpp"  // for UInt
 
 namespace gapbind14::detail {
   // Inspired by the possible implementation of std::unreachable (C++23)
@@ -36,7 +35,7 @@ namespace gapbind14::detail {
     // an empty function body and the noreturn attribute.
 #if defined(_MSC_VER) && !defined(__clang__)  // MSVC
     __assume(false);
-#elif defined(SEMIGROUPS_HAVE___BUILTIN_UNREACHABLE)
+#else
     __builtin_unreachable();
 #endif
   }