diff --git a/hbas.c b/hbas.c
index 0936894..3749440 100644
--- a/hbas.c
+++ b/hbas.c
@@ -384,7 +384,7 @@ int slurp(FILE *fd, ByteVec *out) {
         rv.len += bread;
     }
     *out = rv;
-    err = err || ferror(fd);
+    err = err ? err : ferror(fd);
     return err;
 }