diff --git a/build-constraints.yaml b/build-constraints.yaml
index 68550c58f..dcdac5542 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -651,6 +651,8 @@ packages:
         - uri-encode
 
     "Simon Michael <simon@joyful.com>":
+        - regex-compat-tdfa
+        - darcs
         - hledger
         - hledger-ui
         - hledger-web
@@ -1986,6 +1988,9 @@ package-flags:
     twitter-types:
         time15: true
 
+    darcs:
+        use-time-1point5: true
+
 # end of package-flags