diff --git a/src/preview.ts b/src/preview.ts
index ee7733669..8cebba3db 100644
--- a/src/preview.ts
+++ b/src/preview.ts
@@ -17,7 +17,7 @@ export async function previewEnvironment() {
     const tmpDir = makeTmpDir();
     const pathToTmpCsv = tmpDir + "/environment.csv";
     const envName = "name=ls()";
-    const envClass = "class=sapply(ls(), function(x) {class(get(x))})";
+    const envClass = "class=sapply(ls(), function(x) {class(get(x))[1]})";
     const envOut = "out=sapply(ls(), function(x) {capture.output(str(get(x)), silent = T)[1]})";
     const rWriteCsvCommand = "write.csv(data.frame("
                              + envName + ","