diff --git a/options.go b/options.go
index 63f5eeb..1736ae0 100644
--- a/options.go
+++ b/options.go
@@ -22,7 +22,7 @@
 // WithFormat overrides default bar format "[=>-]"
 func WithFormat(format string) ProgressOption {
 	return func(c *pConf) {
-		if utf8.RuneCountInString(format) == numFmtRunes {
+		if utf8.RuneCountInString(format) == formatLen {
 			c.format = format
 		}
 	}