diff --git a/R/cdm.R b/R/cdm.R
index 63ae35ab..ae493687 100644
--- a/R/cdm.R
+++ b/R/cdm.R
@@ -88,13 +88,14 @@ cdm_from_con <- function(con,
     verify_write_access(con, write_schema = write_schema)
   }
 
-  write_schema_tables <- listTables(con, schema = write_schema)
   # Add existing GeneratedCohortSet objects to cdm object
   if (!is.null(cohort_tables)) {
     if (is.null(write_schema)) {
       rlang::abort("write_schema is required when using cohort_tables")
     }
 
+    write_schema_tables <- listTables(con, schema = write_schema)
+
     for (i in seq_along(cohort_tables)) {
 
       cohort_table <- paste0(write_prefix, cohort_tables[i])
@@ -128,7 +129,7 @@ cdm_from_con <- function(con,
         # create the required cohort_set table
         cohort_set_ref <- cohort_ref %>%
           dplyr::distinct(.data$cohort_definition_id) %>%
-          dplyr::mutate(cohort_name = paste("cohort", .data$cohort_definition_id)) %>%
+          dplyr::mutate(cohort_name = paste("cohort", as.integer(.data$cohort_definition_id))) %>%
           computeQuery(name = paste0(cohort_table, "_set"),
                        schema = write_schema,
                        temporary = FALSE,