--- a/src/racket/src/number.c	2018-02-24 18:16:32.031698079 -0600
+++ b/src/racket/src/number.c	2018-02-24 18:15:41.055445301 -0600
@@ -1775,6 +1775,7 @@
 }
 
 XFORM_NONGCING static MZ_INLINE int minus_zero_p(double d)
+  XFORM_SKIP_PROC
 {
 #ifdef MZ_IS_NEG_ZERO
   return MZ_IS_NEG_ZERO(d);