diff --git a/go.mod b/go.mod
index 1ba67e86fb..abccc84717 100644
--- a/go.mod
+++ b/go.mod
@@ -9,6 +9,6 @@ require (
 	github.com/fsnotify/fsnotify v1.5.3
 	github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2
 	github.com/spf13/pflag v1.0.5
-	github.com/tdewolff/parse/v2 v2.5.30
+	github.com/tdewolff/parse/v2 v2.5.31
 	github.com/tdewolff/test v1.0.6
 )
diff --git a/go.sum b/go.sum
index 62ecc9fa40..4780be7428 100644
--- a/go.sum
+++ b/go.sum
@@ -10,8 +10,8 @@ github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2 h1:JAEbJn3j/FrhdWA9jW8
 github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2/go.mod h1:0KeJpeMD6o+O4hW7qJOT7vyQPKrWmj26uf5wMc/IiIs=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
-github.com/tdewolff/parse/v2 v2.5.30 h1:8pcdUXgBWsDKkvnxfTHSAj3pANBs8japx6vLqozJ+yg=
-github.com/tdewolff/parse/v2 v2.5.30/go.mod h1:WzaJpRSbwq++EIQHYIRTpbYKNA3gn9it1Ik++q4zyho=
+github.com/tdewolff/parse/v2 v2.5.31 h1:PrJN/trWTUYaYxg7jRpKnKXpBK4kBjT9rAFhFAh2Lus=
+github.com/tdewolff/parse/v2 v2.5.31/go.mod h1:WzaJpRSbwq++EIQHYIRTpbYKNA3gn9it1Ik++q4zyho=
 github.com/tdewolff/test v1.0.6 h1:76mzYJQ83Op284kMT+63iCNCI7NEERsIN8dLM+RiKr4=
 github.com/tdewolff/test v1.0.6/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c h1:F1jZWGFhYfh0Ci55sIpILtKKK8p3i2/krTr0H1rg74I=
diff --git a/html/html.go b/html/html.go
index 96a3976aae..c923b0e70c 100644
--- a/html/html.go
+++ b/html/html.go
@@ -484,9 +484,10 @@ func (o *Minifier) Minify(m *minify.M, w io.Writer, r io.Reader, _ map[string]st
 						isXML := attr.Hash == Vocab || attr.Hash == Typeof || attr.Hash == Property || attr.Hash == Resource || attr.Hash == Prefix || attr.Hash == Content || attr.Hash == About || attr.Hash == Rev || attr.Hash == Datatype || attr.Hash == Inlist
 
 						// no quotes if possible, else prefer single or double depending on which occurs more often in value
-						quote := attr.Data[len(attr.Data)-1]
-						if quote != '\'' && quote != '"' {
-							quote = 0
+						var quote byte
+
+						if 0 < len(attr.Data) && (attr.Data[len(attr.Data)-1] == '\'' || attr.Data[len(attr.Data)-1] == '"') {
+							quote = attr.Data[len(attr.Data)-1]
 						}
 						val = html.EscapeAttrVal(&attrByteBuffer, val, quote, o.KeepQuotes, isXML)
 						w.Write(val)