diff --git a/bfd/hosts/rtbsd.h b/bfd/hosts/rtbsd.h
index 8525052763d..45edd3fe25e 100644
--- a/bfd/hosts/rtbsd.h
+++ b/bfd/hosts/rtbsd.h
@@ -11,6 +11,8 @@
 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
 #endif
 
+#define MISSING_VFPRINTF /* Presumably. */
+
 #define SEEK_SET        0
 #define SEEK_CUR        1