diff --git a/example/exn-lib.c b/example/exn-lib.c
index b804ab80..b1ce75e7 100644
--- a/example/exn-lib.c
+++ b/example/exn-lib.c
@@ -1,4 +1,4 @@
 // Request M*LIB to define functions for functions defined within M_USE_DECL.
-#define M_USE_DEF 1
+#define M_USE_DEF
 #include "exn-header.h"