diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index cbe3b490b..1f864aca0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -126,6 +126,7 @@ jobs:
           - '8.15.5'
           - '8.16.2'
           - '8.17.0'
+          - '9.0.0-SNAPSHOT'
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - uses: actions/setup-go@3041bf56c941b39c61721a86cd11f3bb1338122a # v5
@@ -155,7 +156,7 @@ jobs:
 
       - id: setup-fleet
         name: Setup Fleet
-        if: matrix.version == '8.10.3' || matrix.version == '8.11.4' || matrix.version == '8.12.2' || matrix.version == '8.13.4' || matrix.version == '8.14.3' || matrix.version == '8.15.5' || matrix.version == '8.16.2' || matrix.version == '8.17.0'
+        if: matrix.version == '8.10.3' || matrix.version == '8.11.4' || matrix.version == '8.12.2' || matrix.version == '8.13.4' || matrix.version == '8.14.3' || matrix.version == '8.15.5' || matrix.version == '8.16.2' || matrix.version == '8.17.0' || matrix.version == '9.0.0-SNAPSHOT'
         run: |-
           make setup-kibana-fleet
         env:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 779010e41..918cf65d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,8 @@
 - Support 8.15.5 in acc tests ([#963](https://github.com/elastic/terraform-provider-elasticstack/pull/963)).
 - Support 8.16.2 in acc tests ([#964](https://github.com/elastic/terraform-provider-elasticstack/pull/964)).
 - Support 8.17.0 in acc tests ([#969](https://github.com/elastic/terraform-provider-elasticstack/pull/969)).
-- Support several ssl fields in `elasticstack_kibana_synthetics_monitor` ([#967](https://github.com/elastic/terraform-provider-elasticstack/pull/967))
+- Support 9.0.0 in acc tests ([#954](https://github.com/elastic/terraform-provider-elasticstack/pull/954)).
+- Support several ssl fields in `elasticstack_kibana_synthetics_monitor` ([#967](https://github.com/elastic/terraform-provider-elasticstack/pull/967)).
 
 ## [0.11.12] - 2024-12-16
 
diff --git a/Makefile b/Makefile
index 301c8a11a..5a765ac6f 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,7 @@ SWAGGER_VERSION ?= 8.7
 
 GOVERSION ?= $(shell grep -e '^go' go.mod | cut -f 2 -d ' ')
 
-STACK_VERSION ?= 8.17.0
+STACK_VERSION ?= 9.0.0-SNAPSHOT
 
 ELASTICSEARCH_NAME ?= terraform-elasticstack-es
 ELASTICSEARCH_ENDPOINTS ?= http://$(ELASTICSEARCH_NAME):9200