diff --git a/build-constraints.yaml b/build-constraints.yaml
index dbdd279d..59bc8ff0 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2218,6 +2218,9 @@ package-flags:
     reedsolomon:
         llvm: false
 
+    # https://github.com/ghcjs/jsaddle/issues/9
+    jsaddle:
+        gtk3: true
 # end of package-flags