diff --git a/lib/color/color.go b/lib/color/color.go
index fb5860034..7a54573e6 100644
--- a/lib/color/color.go
+++ b/lib/color/color.go
@@ -14,7 +14,7 @@ import (
 var themeColorRegex = regexp.MustCompile(`^(N[1-7]|B[1-6]|AA[245]|AB[45])$`)
 
 func IsThemeColor(colorString string) bool {
-	return themeColorRegex.Match([]byte(colorString))
+	return themeColorRegex.MatchString(colorString)
 }
 
 func Darken(colorString string) (string, error) {