diff --git a/csaf/advisory.go b/csaf/advisory.go
index a55e29e..4732ed3 100644
--- a/csaf/advisory.go
+++ b/csaf/advisory.go
@@ -246,8 +246,7 @@ type DocumentPublisher struct {
 // RevisionNumber specifies a version string to denote clearly the evolution of the content of the document.
 type RevisionNumber string
 
-var versionPattern = patternUnmarshal(`^(0|[1-9][0-9]*)$|^((0|[1-9]\\d*)\\.(0|[1-9]\\d*)\\.(0|[1-9]\\d*)(?:-((?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*)
-	(?:\\.(?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\\+([0-9a-zA-Z-]+(?:\\.[0-9a-zA-Z-]+)*))?)$`)
+var versionPattern = patternUnmarshal("^(0|[1-9][0-9]*)$|^((0|[1-9]\\d*)\\.(0|[1-9]\\d*)\\.(0|[1-9]\\d*)(?:-((?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\\.(?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\\+([0-9a-zA-Z-]+(?:\\.[0-9a-zA-Z-]+)*))?)$")
 
 // Engine contains information about the engine that generated the CSAF document.
 type Engine struct {