diff --git a/json_formatter.go b/json_formatter.go
index afaf0fc8a..c96dc5636 100644
--- a/json_formatter.go
+++ b/json_formatter.go
@@ -23,6 +23,9 @@ func (f FieldMap) resolve(key fieldKey) string {
 // JSONFormatter formats logs into parsable json
 type JSONFormatter struct {
 	// TimestampFormat sets the format used for marshaling timestamps.
+	// The format to use is the same than for time.Format or time.Parse from the standard
+	// library.
+	// The standard Library already provides a set of predefined format.
 	TimestampFormat string
 
 	// DisableTimestamp allows disabling automatic timestamps in output
diff --git a/text_formatter.go b/text_formatter.go
index 8fc698ad6..be2c6efe5 100644
--- a/text_formatter.go
+++ b/text_formatter.go
@@ -53,7 +53,10 @@ type TextFormatter struct {
 	// the time passed since beginning of execution.
 	FullTimestamp bool
 
-	// TimestampFormat to use for display when a full timestamp is printed
+	// TimestampFormat to use for display when a full timestamp is printed.
+	// The format to use is the same than for time.Format or time.Parse from the standard
+	// library.
+	// The standard Library already provides a set of predefined format.
 	TimestampFormat string
 
 	// The fields are sorted by default for a consistent output. For applications