diff --git a/build-constraints.yaml b/build-constraints.yaml
index 522d6d39..f283f54f 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2549,6 +2549,7 @@ packages:
         - diagrams-cairo < 1.3.1.2
         - diagrams-rasterific < 1.3.1.9
         - diagrams-svg < 1.4.0.4
+        - tttool < 1.6.1.3
 
         # https://github.com/fpco/stackage/issues/1842
         - dependent-sum < 0.4