diff --git a/docs/Project.toml b/docs/Project.toml
index cc0be339d..3b2277f57 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -25,4 +25,5 @@ ForwardDiff = "0.10, 1"
 JET = "0.9, 0.10"
 LogDensityProblems = "2"
 MCMCChains = "5, 6, 7"
+MarginalLogDensities = "0.4"
 StableRNGs = "1"