1 files changed, 1 insertions, 0 deletions
diff --git a/io.c b/io.c
index 40ee3d435d..6926316569 100644
--- a/io.c
+++ b/io.c
@@ -21,6 +21,7 @@
 #include <errno.h>
 #include "ruby_atomic.h"
 
+#undef free
 #define free(x) xfree(x)
 
 #if defined(DOSISH) || defined(__CYGWIN__)