diff --git a/api/builtins/ImageTagTransformer.go b/api/builtins/ImageTagTransformer.go
index 627a45768..a0d4f8f87 100644
--- a/api/builtins/ImageTagTransformer.go
+++ b/api/builtins/ImageTagTransformer.go
@@ -147,7 +147,7 @@ func (p *ImageTagTransformerPlugin) findContainers(obj map[string]interface{}) e
 }
 
 func isImageMatched(s, t string) bool {
-	// Tag values are limited to [a-zA-Z0-9_.-].
+	// Tag values are limited to [a-zA-Z0-9_.-{}].
 	pattern, _ := regexp.Compile("^" + t + "(@sha256)?(:[a-zA-Z0-9_.-{}]*)?$")
 	return pattern.MatchString(s)
 }