diff --git a/lib/RevBank/Cart.pm b/lib/RevBank/Cart.pm
index e06ce31..d563bc8 100644
--- a/lib/RevBank/Cart.pm
+++ b/lib/RevBank/Cart.pm
@@ -83,9 +83,8 @@ sub checkout($self, $user) {
             for $entry, $entry->contras;
     }
 
-    my $transaction_id = time() - 1300000000;
-
     RevBank::FileIO::with_lock {
+        my $transaction_id = time() - 1300000000;
         RevBank::Plugins::call_hooks("checkout", $self, $user, $transaction_id);
 
         for my $account (reverse sort keys %deltas) {
@@ -96,11 +95,12 @@ sub checkout($self, $user) {
         }
 
         RevBank::Plugins::call_hooks("checkout_done", $self, $user, $transaction_id);
+
+        sleep 1;  # look busy (and ensure new id for next transaction :))
     };
 
     $self->empty;
 
-    sleep 1;  # Ensure new timestamp/id for new transaction
     return 1;
 }
 
diff --git a/lib/RevBank/FileIO.pm b/lib/RevBank/FileIO.pm
index e4947d5..32b4f1a 100644
--- a/lib/RevBank/FileIO.pm
+++ b/lib/RevBank/FileIO.pm
@@ -24,13 +24,15 @@ sub get_lock() {
 
 	open $lockfh, ">", $lockfn;
 	my $attempt = 1;
+
+	my $debug = !!$ENV{REVBANK_DEBUG};
 	FLOCK: {
 		if (flock $lockfh, LOCK_EX | LOCK_NB) {
 			syswrite $lockfh, $$;
 			return ++$lockcount;
 		}
 
-		if (($attempt % 50) == 0) {
+		if (($attempt % 50) == 0 or $debug) {
 			warn "Another revbank instance has the global lock. Waiting for it to finish...\n"
 		}
 		sleep .1;