diff --git a/go/core/internal/database/testhelpers_test.go b/go/core/internal/database/testhelpers_test.go
index 574b92ce50..0c6e775783 100644
--- a/go/core/internal/database/testhelpers_test.go
+++ b/go/core/internal/database/testhelpers_test.go
@@ -22,25 +22,30 @@ func TestMain(m *testing.M) {
 	if testing.Short() {
 		os.Exit(m.Run())
 	}
+	os.Exit(runWithDatabase(m))
+}
 
-	connStr, _, err := dbtest.Start(context.Background())
+// runWithDatabase returns the exit code so deferred cleanup runs before os.Exit.
+func runWithDatabase(m *testing.M) int {
+	connStr, cleanup, err := dbtest.Start(context.Background())
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "failed to start postgres container: %v\n", err)
-		os.Exit(1)
+		return 1
 	}
+	defer cleanup()
 	sharedConnStr = connStr
 
 	if err := dbtest.Migrate(connStr, true); err != nil {
 		fmt.Fprintf(os.Stderr, "failed to migrate test database: %v\n", err)
-		os.Exit(1)
+		return 1
 	}
 
 	db, err := Connect(context.Background(), &PostgresConfig{Pool: dbtest.PoolConfig(connStr), VectorEnabled: true, Schema: "public", VectorSchema: "public"})
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "failed to connect to test database: %v\n", err)
-		os.Exit(1)
+		return 1
 	}
 	sharedDB = db
 
-	os.Exit(m.Run())
+	return m.Run()
 }
diff --git a/go/core/internal/dbtest/dbtest.go b/go/core/internal/dbtest/dbtest.go
index 492b9d0a2c..7b2f447c24 100644
--- a/go/core/internal/dbtest/dbtest.go
+++ b/go/core/internal/dbtest/dbtest.go
@@ -4,6 +4,7 @@ package dbtest
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 	"net/url"
 	"strings"
@@ -40,17 +41,18 @@ func Start(ctx context.Context) (connStr string, cleanup func(), err error) {
 		),
 	)
 	if err != nil {
-		return "", nil, fmt.Errorf("starting postgres container: %w", err)
+		// Run returns the created container when it fails to start.
+		return "", nil, errors.Join(fmt.Errorf("starting postgres container: %w", err), testcontainers.TerminateContainer(pgContainer))
 	}
 
 	connStr, err = pgContainer.ConnectionString(ctx, "sslmode=disable")
 	if err != nil {
-		_ = pgContainer.Terminate(ctx)
-		return "", nil, fmt.Errorf("getting connection string: %w", err)
+		return "", nil, errors.Join(fmt.Errorf("getting connection string: %w", err), testcontainers.TerminateContainer(pgContainer))
 	}
 
 	cleanup = func() {
-		if err := pgContainer.Terminate(ctx); err != nil {
+		// Not ctx: a test context is canceled before cleanup runs.
+		if err := testcontainers.TerminateContainer(pgContainer); err != nil {
 			fmt.Printf("warning: failed to terminate postgres container: %v\n", err)
 		}
 	}
diff --git a/go/core/internal/dbtest/dbtest_test.go b/go/core/internal/dbtest/dbtest_test.go
index 614f5fdf80..8fd24fec19 100644
--- a/go/core/internal/dbtest/dbtest_test.go
+++ b/go/core/internal/dbtest/dbtest_test.go
@@ -3,6 +3,7 @@ package dbtest_test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"github.com/jackc/pgx/v5"
 	"github.com/stretchr/testify/require"
@@ -57,3 +58,22 @@ func TestClonedDatabasesAreIsolatedAndRemoved(t *testing.T) {
 	require.NoError(t, template.QueryRow(ctx, "SELECT count(*) FROM pg_database WHERE datname = ANY($1)", databaseNames).Scan(&count))
 	require.Zero(t, count, "test cleanup must remove every clone")
 }
+
+func TestStartTTerminatesContainerAfterTestContextIsCanceled(t *testing.T) {
+	if testing.Short() {
+		t.Skip("requires PostgreSQL")
+	}
+	var connStr string
+	require.True(t, t.Run("fixture", func(t *testing.T) {
+		// t.Context is canceled before the fixture's cleanup runs.
+		connStr = dbtest.StartT(t.Context(), t)
+		conn, err := pgx.Connect(t.Context(), connStr)
+		require.NoError(t, err)
+		require.NoError(t, conn.Close(t.Context()))
+	}))
+
+	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
+	defer cancel()
+	_, err := pgx.Connect(ctx, connStr)
+	require.Error(t, err, "postgres container still accepts connections after cleanup")
+}