diff --git a/migra/src/clients/mod.rs b/migra/src/clients/mod.rs
index 38137a6..a9474d2 100644
--- a/migra/src/clients/mod.rs
+++ b/migra/src/clients/mod.rs
@@ -19,7 +19,7 @@ where
 
 pub trait Client: ManageMigrations + ManageTransaction {}
 
-pub type AnyClient = Box<dyn Client>;
+pub type AnyClient = Box<(dyn Client + 'static)>;
 
 #[cfg(feature = "postgres")]
 pub mod postgres;
@@ -36,12 +36,9 @@ pub mod sqlite;
 #[cfg(feature = "sqlite")]
 pub use self::sqlite::Client as SqliteClient;
 
-pub fn with_transaction<TrxFnMut, Res>(
-    client: &mut AnyClient,
-    trx_fn: &mut TrxFnMut,
-) -> MigraResult<Res>
+pub fn run_in_transaction<TrxFnMut>(client: &mut AnyClient, trx_fn: TrxFnMut) -> MigraResult<()>
 where
-    TrxFnMut: FnMut(&mut AnyClient) -> MigraResult<Res>,
+    TrxFnMut: FnOnce(&mut AnyClient) -> MigraResult<()>,
 {
     client
         .begin_transaction()
@@ -50,16 +47,16 @@ where
         .or_else(|err| client.rollback_transaction().and(Err(err)))
 }
 
-pub fn maybe_with_transaction<TrxFnMut, Res>(
-    is_needed: bool,
+pub fn should_run_in_transaction<TrxFnMut>(
     client: &mut AnyClient,
-    trx_fn: &mut TrxFnMut,
-) -> MigraResult<Res>
+    is_needed: bool,
+    trx_fn: TrxFnMut,
+) -> MigraResult<()>
 where
-    TrxFnMut: FnMut(&mut AnyClient) -> MigraResult<Res>,
+    TrxFnMut: FnOnce(&mut AnyClient) -> MigraResult<()>,
 {
     if is_needed {
-        with_transaction(client, trx_fn)
+        run_in_transaction(client, trx_fn)
     } else {
         trx_fn(client)
     }
diff --git a/migra/src/lib.rs b/migra/src/lib.rs
index 94fc636..b7166bd 100644
--- a/migra/src/lib.rs
+++ b/migra/src/lib.rs
@@ -9,6 +9,6 @@ pub mod fs;
 pub mod managers;
 pub mod migration;
 
-pub use clients::{maybe_with_transaction, with_transaction};
+pub use clients::{run_in_transaction, should_run_in_transaction};
 pub use errors::{Error, MigraResult as Result, StdResult};
 pub use migration::Migration;
diff --git a/migra_cli/src/commands/apply.rs b/migra_cli/src/commands/apply.rs
index 13604c5..7cbe398 100644
--- a/migra_cli/src/commands/apply.rs
+++ b/migra_cli/src/commands/apply.rs
@@ -1,6 +1,7 @@
 use crate::app::App;
 use crate::database;
 use crate::opts::ApplyCommandOpt;
+use migra::should_run_in_transaction;
 
 pub(crate) fn apply_sql(app: &App, cmd_opts: &ApplyCommandOpt) -> migra::StdResult<()> {
     let config = app.config()?;
@@ -20,17 +21,17 @@ pub(crate) fn apply_sql(app: &App, cmd_opts: &ApplyCommandOpt) -> migra::StdResu
         .map(std::fs::read_to_string)
         .collect::<Result<Vec<_>, _>>()?;
 
-    migra::maybe_with_transaction(
-        cmd_opts.transaction_opts.single_transaction,
+    should_run_in_transaction(
         &mut client,
-        &mut |mut client| {
+        cmd_opts.transaction_opts.single_transaction,
+        |client| {
             file_contents
                 .iter()
                 .try_for_each(|content| {
-                    migra::maybe_with_transaction(
+                    should_run_in_transaction(
+                        client,
                         !cmd_opts.transaction_opts.single_transaction,
-                        &mut client,
-                        &mut |client| client.apply_sql(content),
+                        |client| client.apply_sql(content),
                     )
                 })
                 .map_err(From::from)
diff --git a/migra_cli/src/commands/downgrade.rs b/migra_cli/src/commands/downgrade.rs
index 9e1dbdc..c3f930e 100644
--- a/migra_cli/src/commands/downgrade.rs
+++ b/migra_cli/src/commands/downgrade.rs
@@ -1,6 +1,7 @@
 use crate::app::App;
 use crate::database;
 use crate::opts::DowngradeCommandOpt;
+use migra::should_run_in_transaction;
 use std::cmp;
 
 pub(crate) fn rollback_applied_migrations(
@@ -32,19 +33,19 @@ pub(crate) fn rollback_applied_migrations(
         })
         .collect::<Result<Vec<_>, _>>()?;
 
-    migra::maybe_with_transaction(
-        opts.transaction_opts.single_transaction,
+    should_run_in_transaction(
         &mut client,
-        &mut |mut client| {
+        opts.transaction_opts.single_transaction,
+        |client| {
             migrations_with_content
                 .iter()
                 .try_for_each(|(migration_name, content)| {
                     if all_migrations.contains_name(migration_name) {
                         println!("downgrade {}...", migration_name);
-                        migra::maybe_with_transaction(
+                        should_run_in_transaction(
+                            client,
                             !opts.transaction_opts.single_transaction,
-                            &mut client,
-                            &mut |client| client.run_downgrade_migration(migration_name, &content),
+                            |client| client.run_downgrade_migration(migration_name, &content),
                         )
                     } else {
                         Ok(())
diff --git a/migra_cli/src/commands/upgrade.rs b/migra_cli/src/commands/upgrade.rs
index 11b9106..6775131 100644
--- a/migra_cli/src/commands/upgrade.rs
+++ b/migra_cli/src/commands/upgrade.rs
@@ -2,6 +2,7 @@ use crate::app::App;
 use crate::database;
 use crate::opts::UpgradeCommandOpt;
 use migra::migration;
+use migra::should_run_in_transaction;
 
 pub(crate) fn upgrade_pending_migrations(
     app: &App,
@@ -53,18 +54,18 @@ pub(crate) fn upgrade_pending_migrations(
         })
         .collect::<Result<Vec<_>, _>>()?;
 
-    migra::maybe_with_transaction(
-        opts.transaction_opts.single_transaction,
+    should_run_in_transaction(
         &mut client,
-        &mut |mut client| {
+        opts.transaction_opts.single_transaction,
+        |client| {
             migrations_with_content
                 .iter()
                 .try_for_each(|(migration_name, content)| {
                     println!("upgrade {}...", migration_name);
-                    migra::maybe_with_transaction(
+                    should_run_in_transaction(
+                        client,
                         !opts.transaction_opts.single_transaction,
-                        &mut client,
-                        &mut |client| client.run_upgrade_migration(migration_name, &content),
+                        |client| client.run_upgrade_migration(migration_name, &content),
                     )
                 })
                 .map_err(From::from)