diff --git a/R/find_transformation.R b/R/find_transformation.R
index f82cfb9eb..63f45eb56 100644
--- a/R/find_transformation.R
+++ b/R/find_transformation.R
@@ -165,9 +165,9 @@ find_transformation.character <- function(x, ...) {
 # helper -----------------------------
 
 .is_division <- function(x) {
-  any(grepl("(.*)/([0-9\\.]+)(\\)*)$", x)) && !any(grepl("(.*)(\\^|\\*\\*)\\((.*)/(.*)\\)", x))
+  any(grepl("(.*)/([0-9\\.\\+\\-]+)(\\)*)$", x)) && !any(grepl("(.*)(\\^|\\*\\*)\\((.*)/(.*)\\)", x))
 }
 
 .is_box_cox <- function(x) {
-  any(grepl("\\((.*)\\^[0-9\\.]+-1\\)", x))
+  any(grepl("\\((.*)\\^[0-9\\.\\+\\-]+-1\\)", x))
 }