1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index 7381fe1c92..fe3b0ed6c0 100644
--- a/io.c
+++ b/io.c
@@ -2889,7 +2889,7 @@ next_argv()
     int defout_binmode = 0;
 
     GetOpenFile(rb_defout, fptr);
-    if (fptr->mode | FMODE_BINMODE)
+    if (fptr->mode & FMODE_BINMODE)
 	defout_binmode = 1;
 
     if (init_p == 0) {