diff --git a/sexp/xt-string.go b/sexp/xt-string.go
index 8423323..bb481ae 100644
--- a/sexp/xt-string.go
+++ b/sexp/xt-string.go
@@ -2,7 +2,7 @@ package sexp
 
 func parseString(buf []byte, offset, end int) (interface{}, int, error) {
 	endOfString := offset
-	if buf[endOfString] != 0 && endOfString < end {
+	for buf[endOfString] != 0 && endOfString < end {
 		endOfString = endOfString + 1
 	}
 	return []string{string(buf[offset:endOfString])}, end, nil
diff --git a/sexp/xt-sym-name.go b/sexp/xt-sym-name.go
index b439169..caf113e 100644
--- a/sexp/xt-sym-name.go
+++ b/sexp/xt-sym-name.go
@@ -2,7 +2,7 @@ package sexp
 
 func parseSymName(buf []byte, offset, end int) (interface{}, int, error) {
 	endOfString := offset
-	if buf[endOfString] != 0 && endOfString < end {
+	for buf[endOfString] != 0 && endOfString < end {
 		endOfString = endOfString + 1
 	}
 	return string(buf[offset:endOfString]), end, nil
diff --git a/sexp/xt-vector.go b/sexp/xt-vector.go
index 5fc7402..3f6fbd7 100644
--- a/sexp/xt-vector.go
+++ b/sexp/xt-vector.go
@@ -10,9 +10,9 @@ func parseVectorAttr(attr interface{}, vectorArr []interface{}, offset int) (int
 	if !ok {
 		return vectorArr, offset, nil
 	}
-	names, ok := attrMap["n"].([]string)
+	names, ok := attrMap["names"].([]string)
 	if !ok {
-		name, ok := attrMap["n"].(string)
+		name, ok := attrMap["names"].(string)
 		if !ok {
 			return nil, offset, errors.New("Vector names not parsed correctly")
 		}
diff --git a/sexp_parsing_test.go b/sexp_parsing_test.go
index 23e8b26..57368ff 100644
--- a/sexp_parsing_test.go
+++ b/sexp_parsing_test.go
@@ -149,3 +149,8 @@ func TestLangTag(t *testing.T) {
 	_, err := getResultObject("expression(2^x)")
 	assert.Nil(t, err)
 }
+
+func TestClass(t *testing.T) {
+	_, err := getResultObject("setClass('test_class', slots=c(listslot='list', aslot='apNull', numslot='numeric', chrslot='character'), contains='data.frame'); j <- new('test_class'); d <- j")
+	assert.Nil(t, err)
+}
diff --git a/test/Dockerfile-RServe-Cran b/test/Dockerfile-RServe-Cran
index a6ba921..becf2c4 100644
--- a/test/Dockerfile-RServe-Cran
+++ b/test/Dockerfile-RServe-Cran
@@ -1,8 +1,8 @@
-FROM r-base:3.2.1
+FROM r-base:3.5.1
 
 RUN apt-get update
 
-RUN apt-get install -y --no-install-recommends \
+RUN apt-get install -y --no-install-recommends\
               libxml2-dev \
               libcurl4-gnutls-dev \
               libssl-dev
diff --git a/test/Dockerfile-RServe-RForge b/test/Dockerfile-RServe-RForge
index 23d8678..42b6efb 100644
--- a/test/Dockerfile-RServe-RForge
+++ b/test/Dockerfile-RServe-RForge
@@ -1,4 +1,4 @@
-FROM r-base:3.2.1
+FROM r-base:3.5.1
 
 RUN apt-get update