diff --git a/.github/workflows/horizon.yml b/.github/workflows/horizon.yml
index 74c3f47725..d71a4f53de 100644
--- a/.github/workflows/horizon.yml
+++ b/.github/workflows/horizon.yml
@@ -13,7 +13,7 @@ jobs:
         os: [ubuntu-20.04, ubuntu-22.04]
         go: ["1.21", "1.22"]
         pg: [12, 16]
-        protocol-version: [20]
+        protocol-version: [21]
     runs-on: ${{ matrix.os }}
     services:
       postgres:
@@ -32,11 +32,10 @@ jobs:
     env:
       HORIZON_INTEGRATION_TESTS_ENABLED: true
       HORIZON_INTEGRATION_TESTS_CORE_MAX_SUPPORTED_PROTOCOL: ${{ matrix.protocol-version }}
-      PROTOCOL_20_CORE_DEBIAN_PKG_VERSION: 20.2.0-1716.rc3.34d82fc00.focal
-      PROTOCOL_20_CORE_DOCKER_IMG: stellar/unsafe-stellar-core:20.2.0-1716.rc3.34d82fc00.focal
-      PROTOCOL_20_SOROBAN_RPC_DOCKER_IMG: stellar/soroban-rpc:20.3.0-rc1-52
-      PROTOCOL_19_CORE_DEBIAN_PKG_VERSION: 19.14.0-1500.5664eff4e.focal
-      PROTOCOL_19_CORE_DOCKER_IMG: stellar/stellar-core:19.14.0-1500.5664eff4e.focal
+      PROTOCOL_21_CORE_DEBIAN_PKG_VERSION: 20.4.1-1807.b152dc51d.focal
+      PROTOCOL_21_CORE_DOCKER_IMG: stellar/unsafe-stellar-core:20.4.1-1807.b152dc51d.focal
+      PROTOCOL_21_SOROBAN_RPC_DOCKER_IMG: stellar/soroban-rpc:21.0.0-rc1-68
+      # TODO: test protocol 20 too
       PGHOST: localhost
       PGPORT: 5432
       PGUSER: postgres