diff --git a/internal/handlers/api_test.go b/internal/handlers/api_test.go
index e74f9fd..d859b55 100644
--- a/internal/handlers/api_test.go
+++ b/internal/handlers/api_test.go
@@ -7,6 +7,7 @@ package handlers_test
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	"database/sql"
 	"encoding/json"
 	"errors"
@@ -152,9 +153,12 @@ func newTestServerWith(
 ) *testServer {
 	t.Helper()
 
+	// A random name, so that no other test can share it, not
+	// even one that has finished but still holds its database
+	// open.
 	dbURL := fmt.Sprintf(
-		"file:test_%p?mode=memory&cache=shared",
-		t,
+		"file:%s?mode=memory&cache=shared",
+		rand.Text(),
 	)
 	copyTemplateDB(t, dbURL)
 
@@ -667,6 +671,29 @@ func TestCreateSessionDuplicate(t *testing.T) {
 	}
 }
 
+// TestEachTestServerHasItsOwnDatabase checks that starting a
+// second test server leaves the first one's database alone and
+// starts on an empty one of its own.
+func TestEachTestServerHasItsOwnDatabase(t *testing.T) {
+	first := newTestServer(t)
+	first.createSession("samenick")
+
+	second := newTestServer(t)
+
+	resp := postSession(t, first, "samenick")
+
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusConflict {
+		t.Fatalf(
+			"first server: expected 409, got %d",
+			resp.StatusCode,
+		)
+	}
+
+	second.createSession("samenick")
+}
+
 func TestCreateSessionEmpty(t *testing.T) {
 	tserver := newTestServer(t)
 
diff --git a/internal/service/service_test.go b/internal/service/service_test.go
index 2cc9ef2..e619054 100644
--- a/internal/service/service_test.go
+++ b/internal/service/service_test.go
@@ -6,6 +6,7 @@ package service_test
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -43,9 +44,12 @@ type testEnv struct {
 func newTestEnv(t *testing.T) *testEnv {
 	t.Helper()
 
+	// A random name, so that no other test can share it, not
+	// even one that has finished but still holds its database
+	// open.
 	dbURL := fmt.Sprintf(
-		"file:svc_test_%p?mode=memory&cache=shared",
-		t,
+		"file:%s?mode=memory&cache=shared",
+		rand.Text(),
 	)
 
 	var (
@@ -137,6 +141,19 @@ func createSession(
 	return sessionID
 }
 
+// TestEachTestEnvHasItsOwnDatabase checks that a test
+// environment starts on an empty database while another one
+// is still open.
+func TestEachTestEnvHasItsOwnDatabase(t *testing.T) {
+	ctx := t.Context()
+
+	first := newTestEnv(t)
+	createSession(ctx, t, first.db, "samenick")
+
+	second := newTestEnv(t)
+	createSession(ctx, t, second.db, "samenick")
+}
+
 func TestFanOut(t *testing.T) {
 	env := newTestEnv(t)
 	ctx := t.Context()