diff --git a/.changeset/ten-rice-sparkle.md b/.changeset/ten-rice-sparkle.md
new file mode 100644
index 0000000000..8803c747c5
--- /dev/null
+++ b/.changeset/ten-rice-sparkle.md
@@ -0,0 +1,5 @@
+---
+"@core/sync-service": patch
+---
+
+fix: correctly scope the storage based on the tenant and use already-provided tenant id
diff --git a/integration-tests/tests/_macros.luxinc b/integration-tests/tests/_macros.luxinc
index 84cdc32dd8..649a0498a4 100644
--- a/integration-tests/tests/_macros.luxinc
+++ b/integration-tests/tests/_macros.luxinc
@@ -84,7 +84,7 @@
 [endmacro]
 
 [macro setup_electric]
-  [invoke setup_electric_with_env "ELECTRIC_DATABASE_ID=integration_test_tenant DATABASE_URL=$database_url"]
+  [invoke setup_electric_with_env "DATABASE_URL=$database_url"]
 [endmacro]
 
 [macro setup_multi_tenant_electric]
@@ -96,7 +96,7 @@
 [endmacro]
 
 [macro setup_electric_with_env_and_tenant env]
-  [invoke setup_electric_with_env "ELECTRIC_DATABASE_ID=integration_test_tenant DATABASE_URL=$database_url $env"]
+  [invoke setup_electric_with_env "DATABASE_URL=$database_url $env"]
 [endmacro]
 
 [macro setup_electric_shell shell_name port env]
@@ -107,7 +107,7 @@
 [endmacro]
 
 [macro setup_electric_shell_with_tenant shell_name port]
-  [invoke setup_electric_shell $shell_name $port "ELECTRIC_DATABASE_ID=integration_test_tenant DATABASE_URL=$database_url"]
+  [invoke setup_electric_shell $shell_name $port "DATABASE_URL=$database_url"]
 [endmacro]
 
 [macro add_tenant tenant_id electric_port]
diff --git a/packages/sync-service/.env.dev b/packages/sync-service/.env.dev
index 5aaaa42a13..346d295c7d 100644
--- a/packages/sync-service/.env.dev
+++ b/packages/sync-service/.env.dev
@@ -5,6 +5,5 @@ ELECTRIC_CACHE_MAX_AGE=1
 ELECTRIC_CACHE_STALE_AGE=3
 # using a small chunk size of 10kB for dev to speed up tests
 ELECTRIC_LOG_CHUNK_BYTES_THRESHOLD=10000
-ELECTRIC_DATABASE_ID=test_tenant
 # configuring a second database for multi-tenancy integration testing
 OTHER_DATABASE_URL=postgresql://postgres:password@localhost:54322/electric?sslmode=disable
diff --git a/packages/sync-service/.env.test b/packages/sync-service/.env.test
index 439f18af07..dd48e6bbee 100644
--- a/packages/sync-service/.env.test
+++ b/packages/sync-service/.env.test
@@ -1,3 +1,2 @@
 LOG_LEVEL=info
 DATABASE_URL=postgresql://postgres:password@localhost:54321/postgres?sslmode=disable
-ELECTRIC_DATABASE_ID=test_tenant
diff --git a/packages/sync-service/config/runtime.exs b/packages/sync-service/config/runtime.exs
index d45900bee8..2203fbe3d8 100644
--- a/packages/sync-service/config/runtime.exs
+++ b/packages/sync-service/config/runtime.exs
@@ -172,8 +172,12 @@ replication_stream_id =
 storage = {storage_mod, storage_opts}
 
 prometheus_port = env!("ELECTRIC_PROMETHEUS_PORT", :integer, nil)
+# The provided database id is relevant if you had used v0.8 and want to keep the storage
+# instead of having hanging files. We use a provided value as stack id, but nothing else.
+provided_database_id = env!("ELECTRIC_DATABASE_ID", :string, "single_stack")
 
 config :electric,
+  provided_database_id: provided_database_id,
   allow_shape_deletion: enable_integration_testing,
   cache_max_age: cache_max_age,
   cache_stale_age: cache_stale_age,
diff --git a/packages/sync-service/lib/electric/application.ex b/packages/sync-service/lib/electric/application.ex
index 2539c5b043..54686b2015 100644
--- a/packages/sync-service/lib/electric/application.ex
+++ b/packages/sync-service/lib/electric/application.ex
@@ -15,7 +15,7 @@ defmodule Electric.Application do
     # We have "instance id" identifier as the node ID, however that's generated every runtime,
     # so isn't stable across restarts. Our storages however scope themselves based on this stack ID
     # so we're just hardcoding it here.
-    stack_id = "single_stack"
+    stack_id = Application.get_env(:electric, :provided_database_id, "single_stack")
 
     router_opts =
       [
diff --git a/packages/sync-service/lib/electric/shape_cache/file_storage.ex b/packages/sync-service/lib/electric/shape_cache/file_storage.ex
index f9d6e328b5..21a9161bc0 100644
--- a/packages/sync-service/lib/electric/shape_cache/file_storage.ex
+++ b/packages/sync-service/lib/electric/shape_cache/file_storage.ex
@@ -33,9 +33,10 @@ defmodule Electric.ShapeCache.FileStorage do
   @impl Electric.ShapeCache.Storage
   def shared_opts(opts) do
     stack_id = Keyword.fetch!(opts, :stack_id)
-    storage_dir = Keyword.get(opts, :storage_dir, "./shapes/#{stack_id}")
+    storage_dir = Keyword.get(opts, :storage_dir, "./shapes")
 
-    %{base_path: storage_dir, stack_id: stack_id}
+    # Always scope the provided storage dir by stack id
+    %{base_path: Path.join(storage_dir, stack_id), stack_id: stack_id}
   end
 
   @impl Electric.ShapeCache.Storage