diff --git a/R/lav_test_Wald.R b/R/lav_test_Wald.R
index fdc639db..3b55ca13 100644
--- a/R/lav_test_Wald.R
+++ b/R/lav_test_Wald.R
@@ -15,7 +15,7 @@ lavTestWald <- function(object, constraints = NULL, verbose = FALSE) {
   # extract slots
   lavoptions <- object@Options
   lavmodel <- object@Model
-  lavpartable <- object@ParTable
+  lavpartable <- data.frame(object@ParTable)
 
   # remove == constraints from parTable
   eq.idx <- which(lavpartable$op == "==")