diff --git a/logger/loggers.go b/logger/loggers.go
index 497060fdb9..77d1119747 100644
--- a/logger/loggers.go
+++ b/logger/loggers.go
@@ -17,19 +17,6 @@ import (
 	"os"
 )
 
-// LogSystem is implemented by log output devices.
-// All methods can be called concurrently from multiple goroutines.
-type LogSystem interface {
-	GetLogLevel() LogLevel
-	SetLogLevel(i LogLevel)
-	LogPrint(LogLevel, string)
-}
-
-type message struct {
-	level LogLevel
-	msg   string
-}
-
 type LogLevel uint32
 
 const (
diff --git a/logger/logsystem.go b/logger/logsystem.go
index 3601e926c3..8458b938f3 100644
--- a/logger/logsystem.go
+++ b/logger/logsystem.go
@@ -6,6 +6,14 @@ import (
 	"sync/atomic"
 )
 
+// LogSystem is implemented by log output devices.
+// All methods can be called concurrently from multiple goroutines.
+type LogSystem interface {
+	GetLogLevel() LogLevel
+	SetLogLevel(i LogLevel)
+	LogPrint(LogLevel, string)
+}
+
 // NewStdLogSystem creates a LogSystem that prints to the given writer.
 // The flag values are defined package log.
 func NewStdLogSystem(writer io.Writer, flags int, level LogLevel) LogSystem {
diff --git a/logger/sys.go b/logger/sys.go
index 5b48241c25..59b8582f91 100644
--- a/logger/sys.go
+++ b/logger/sys.go
@@ -4,6 +4,11 @@ import (
 	"sync"
 )
 
+type message struct {
+	level LogLevel
+	msg   string
+}
+
 var (
 	logMessageC = make(chan message)
 	addSystemC  = make(chan LogSystem)