diff --git a/CHANGELOG.md b/CHANGELOG.md
index ca5399133..b7ddfdf4a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,9 @@ To release a new version (e.g. from `1.0.0` -> `2.0.0`):
 
 ## [Unreleased]
 
+* Pin `arviz` dependency to `< 0.20.0` to fix upstream `InferenceData`
+  deprecation.
+
 ## [1.5.2] - 2026-02-10
 
 * Move `schema` package as `meridian.schema`.
diff --git a/pyproject.toml b/pyproject.toml
index 2fce324a6..2195c622c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,7 @@ keywords = [
 # pip dependencies of the project
 # Installed locally with `pip install -e .`
 dependencies = [
-  "arviz",
+  "arviz < 0.20.0",
   "altair >= 5",
   "bidict",
   "immutabledict",