diff --git a/build-constraints.yaml b/build-constraints.yaml
index 99a6bc2a..7535f432 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -5349,7 +5349,7 @@ packages:
         - bindings-DSL
         - bindings-uname
         - bitarray
-        - blank-canvas
+        - blank-canvas < 0
         - blaze-svg
         - blaze-textual
         - bloomfilter
@@ -5552,7 +5552,7 @@ packages:
         - json
         - json-alt
         - jsonrpc-tinyclient
-        - kansas-comet
+        - kansas-comet < 0
         - kleene
         - knob
         - language-haskell-extract