diff --git a/.drone.yml b/.drone.yml
index 5adaa44..af8d2ca 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -36,6 +36,7 @@ steps:
   - name: verify
     image: thegeeklab/alpine-tools
     commands:
+      - apk add tree
       - tree src
       - src/build/linkcheck/linkcheck --help
       - src/build/linkcheck/linkcheck --version
@@ -218,6 +219,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: f28151c98eb52c02e331395dc85847a6461fde84b08c6bffd58a178c65313077
+hmac: 9ec54dad33a20a7f0e312b9b00fa5b79aa81c2f33d04ac53efc1568bf8ac9847
 
 ...