diff --git a/Python/dtoa.c b/Python/dtoa.c
index 1cac9417487..c0559b48727 100644
--- a/Python/dtoa.c
+++ b/Python/dtoa.c
@@ -116,6 +116,8 @@
 
 #include "Python.h"
 
+#define IEEE_8087
+
 /* if PY_NO_SHORT_FLOAT_REPR is defined, then don't even try to compile
    the following code */
 #ifndef PY_NO_SHORT_FLOAT_REPR