diff --git a/server/db/mysql/group_schema_test.go b/server/db/mysql/group_schema_test.go
index 9be7468..0eb962b 100644
--- a/server/db/mysql/group_schema_test.go
+++ b/server/db/mysql/group_schema_test.go
@@ -56,7 +56,7 @@ func TestEnsureIMGroupBusinessTablesUsesSelectedTenantDatabase(t *testing.T) {
 }
 
 func TestGroupMessageShardTableRejectsUnsafeMonth(t *testing.T) {
-	if table, ok := groupMessageShardTable(1, "202609"); !ok || table != "im_group_messages_202609" {
+	if table, ok := groupMessageShardTable(1, "202609"); !ok || table != "im_001_group_messages_202609" {
 		t.Fatalf("unexpected valid shard: table=%q ok=%v", table, ok)
 	}
 	for _, month := range []string{"", "20269", "202613", "2026_09", "202609;DROP TABLE im_users"} {
@@ -73,9 +73,9 @@ func TestTenantPartitionTableNames(t *testing.T) {
 		messages string
 		group    string
 	}{
-		{tenantID: 1, friends: "im_friendships", messages: "im_messages", group: "im_group_messages_202609"},
-		{tenantID: 10, friends: "im_friendships", messages: "im_messages", group: "im_group_messages_202609"},
-		{tenantID: 1000, friends: "im_friendships", messages: "im_messages", group: "im_group_messages_202609"},
+		{tenantID: 1, friends: "im_001_friendships", messages: "im_001_messages", group: "im_001_group_messages_202609"},
+		{tenantID: 10, friends: "im_010_friendships", messages: "im_010_messages", group: "im_010_group_messages_202609"},
+		{tenantID: 1000, friends: "im_1000_friendships", messages: "im_1000_messages", group: "im_1000_group_messages_202609"},
 	}
 	for _, tc := range tests {
 		if got := tenantFriendshipsTable(tc.tenantID); got != tc.friends {
diff --git a/server/db/mysql/tenant_tables.go b/server/db/mysql/tenant_tables.go
index 00547c3..01282d5 100644
--- a/server/db/mysql/tenant_tables.go
+++ b/server/db/mysql/tenant_tables.go
@@ -9,19 +9,23 @@ import (
 	t "github.com/tinode/chat/server/store/types"
 )
 
-func tenantFriendshipsTable(t.TenantID) string {
-	return "im_friendships"
+func tenantTablePrefix(tenantID t.TenantID) string {
+	return fmt.Sprintf("im_%03d_", tenantID)
 }
 
-func tenantMessagesTable(t.TenantID) string {
-	return "im_messages"
+func tenantFriendshipsTable(tenantID t.TenantID) string {
+	return tenantTablePrefix(tenantID) + "friendships"
 }
 
-func tenantGroupMessagesTable(_ t.TenantID, month string) (string, bool) {
+func tenantMessagesTable(tenantID t.TenantID) string {
+	return tenantTablePrefix(tenantID) + "messages"
+}
+
+func tenantGroupMessagesTable(tenantID t.TenantID, month string) (string, bool) {
 	if !validShardMonth(month) {
 		return "", false
 	}
-	return fmt.Sprintf("im_group_messages_%s", month), true
+	return fmt.Sprintf("%sgroup_messages_%s", tenantTablePrefix(tenantID), month), true
 }
 
 func validShardMonth(month string) bool {