diff --git a/frontend/dockerfile/parser/line_parsers.go b/frontend/dockerfile/parser/line_parsers.go
index d0e182e8..2c375b74 100644
--- a/frontend/dockerfile/parser/line_parsers.go
+++ b/frontend/dockerfile/parser/line_parsers.go
@@ -19,7 +19,7 @@ import (
 )
 
 var (
-	errDockerfileNotStringArray = errors.New("When using JSON array syntax, arrays must be comprised of strings only.")
+	errDockerfileNotStringArray = errors.New("when using JSON array syntax, arrays must be comprised of strings only")
 )
 
 const (