diff --git a/.github/workflows/build.scala_test.yml b/.github/workflows/build.scala_test.yml
index 6cd25f2443..adfe2cf28c 100644
--- a/.github/workflows/build.scala_test.yml
+++ b/.github/workflows/build.scala_test.yml
@@ -63,6 +63,11 @@ on:
         required: false
         type: string
         default: "postgres:17"
+      postgres_init_args:
+        description: "Additional arguments to pass to Postgres on initialization via POSTGRES_INITDB_ARGS"
+        required: false
+        type: string
+        default: "-c max_connections=16000"
 
 jobs:
 
@@ -117,7 +122,7 @@ jobs:
         image: ${{ inputs.postgres_image }}
         env:
           POSTGRES_PASSWORD: postgres
-          POSTGRES_INITDB_ARGS: "-c max_connections=16000"
+          POSTGRES_INITDB_ARGS: ${{ inputs.postgres_init_args }}
 
     steps:
 
diff --git a/.github/workflows/build.wallclock_pg14.yml b/.github/workflows/build.wallclock_pg14.yml
index efa885407d..7c2b4fce25 100644
--- a/.github/workflows/build.wallclock_pg14.yml
+++ b/.github/workflows/build.wallclock_pg14.yml
@@ -24,5 +24,7 @@ jobs:
       commit_sha: ""
       daml_base_version: ""
       # This is the Postgres 14 image we built for testing. From 17 onwards, we use the official image.
+      # It doesn't support `-c` init args. `max_connections` is set in the image itself.
       postgres_image: us-central1-docker.pkg.dev/da-cn-shared/ghcr/digital-asset/decentralized-canton-sync-dev/docker/splice-test-postgres:0.3.12
+      postgres_init_args: ""
     secrets: inherit