diff --git a/util/iobuf.c b/util/iobuf.c
index 35de02043..a330460d6 100644
--- a/util/iobuf.c
+++ b/util/iobuf.c
@@ -1107,7 +1107,7 @@ iobuf_open( const char *fname )
     IOBUF a;
     FILEP_OR_FD fp;
     file_filter_ctx_t *fcx;
-    size_t len;
+    size_t len = 0;
     int print_only = 0;
     int fd;