diff --git a/daemon/logging/logging_formatters.go b/daemon/logging/logging_formatters.go
index 7179676..1ee8260 100644
--- a/daemon/logging/logging_formatters.go
+++ b/daemon/logging/logging_formatters.go
@@ -88,7 +88,7 @@ func (f *HumanFormatter) Format(e *logger.Entry) (out []byte, err error) {
 	prefixFields := []string{JobField, SubsysField}
 	prefixed := make(map[string]bool, len(prefixFields)+2)
 	for _, field := range prefixFields {
-		val, ok := e.Fields[field].(string)
+		val, ok := e.Fields[field]
 		if !ok {
 			continue
 		}