diff --git a/R/spicy.R b/R/spicy.R
index 6ab2d04..388d085 100644
--- a/R/spicy.R
+++ b/R/spicy.R
@@ -149,9 +149,9 @@ spicy <- function(cells,
   
   ## Check whether the subject parameter has a one-to-one mapping with image
   if (!is.null(subject)) {
-    if (nrow(unique(cells[, subject])) == nrow(unique(cells[, imageIDCol]))) {
+    if (nrow(as.data.frame(unique(cells[, subject]))) == nrow(as.data.frame(unique(cells[, imageIDCol])))) {
       subject <- NULL
-      cli::cli_inform("Your specified subject parameter has a one-to-one mapping with imageID. Converting to a linear model instead of mixed model.")
+      warning("Your specified subject parameter has a one-to-one mapping with imageID. Converting to a linear model instead of mixed model.")
     }  
   }