diff --git a/src/eval.c b/src/eval.c
index c3b7bcc..4afcecc 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -10,6 +10,7 @@
 /*
  * eval.c: Expression evaluation.
  */
+#define USING_FLOAT_STUFF
 
 #include "vim.h"