diff --git a/AUTHORS b/AUTHORS
index f6098064..15ca501d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -46,6 +46,7 @@ Thanks to the following people for patches and bug reports:
   * Jeronimo Pellegrini
   * John Cowan
   * John Samsa
+  * Kris Katterjohn
   * Lars J Aas
   * Lorenzo Campedelli
   * Marc Nieper-Wißkirchen
diff --git a/include/chibi/features.h b/include/chibi/features.h
index 9c28aeba..c280fe84 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -304,7 +304,11 @@
 /* for bignum support, need a double long to store long*long */
 /* gcc supports uint128_t, otherwise we need a custom struct */
 #ifndef SEXP_USE_CUSTOM_LONG_LONGS
-#define SEXP_USE_CUSTOM_LONG_LONGS (SEXP_64_BIT && !defined(__GNUC__))
+#if SEXP_64_BIT && !defined(__GNUC__)
+#define SEXP_USE_CUSTOM_LONG_LONGS 1
+#else
+#define SEXP_USE_CUSTOM_LONG_LONGS 0
+#endif
 #endif
 
 #ifndef SEXP_USE_NO_FEATURES