diff --git a/R/Start.R b/R/Start.R
index c5a0a4c9dd8ca4dceb22b3c0164590c77d27e7a7..54ebdb8159a5a274f6132964f3ba1bdc00d20bd1 100644
--- a/R/Start.R
+++ b/R/Start.R
@@ -4185,7 +4185,12 @@ Start <- function(..., # dim = indices/selectors,
     start_call <- match.call()
     for (i in 2:length(start_call)) {
       if (class(start_call[[i]]) %in% c('name', 'call')) {
-        start_call[[i]] <- eval.parent(start_call[[i]])
+        tmp <- eval.parent(start_call[[i]])
+        if (is.null(tmp)) {
+          start_call[i] <- list(NULL)
+        } else {
+          start_call[[i]] <- eval.parent(start_call[[i]])
+        }
       }
     }
     start_call[['retrieve']] <- TRUE