diff --git a/hecl/extern/athena b/hecl/extern/athena
index 89968f1c3..5df07a203 160000
--- a/hecl/extern/athena
+++ b/hecl/extern/athena
@@ -1 +1 @@
-Subproject commit 89968f1c31f76d518b6cc86e2350097fddafe7c4
+Subproject commit 5df07a203939f382f66238e7d3cec417f9ec0b3e
diff --git a/hecl/include/hecl/MathExtras.hpp b/hecl/include/hecl/MathExtras.hpp
index 4c927c20e..9d02e59af 100644
--- a/hecl/include/hecl/MathExtras.hpp
+++ b/hecl/include/hecl/MathExtras.hpp
@@ -30,6 +30,10 @@
 # endif
 #endif
 
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
 #include "hecl.hpp"
 #include <algorithm>
 #include <cassert>