diff --git a/R/clean_parameters.R b/R/clean_parameters.R
index e4be16614..3a45d91f7 100644
--- a/R/clean_parameters.R
+++ b/R/clean_parameters.R
@@ -497,22 +497,22 @@ clean_parameters.mlm <- function(x, ...) {
 
     resp_pattern <- sprintf("_%s_(.*)", resp)
     for (i in resp_pattern) {
-      out$Cleaned_Parameter <- gsub(pattern = i, "_\\1", out$Cleaned_Parameter, perl = TRUE)
+      out$Cleaned_Parameter <- gsub(pattern = i, "_\\1", out$Cleaned_Parameter)
     }
 
     resp_pattern <- sprintf("__%s(.*)", resp)
     for (i in resp_pattern) {
-      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter, perl = TRUE)
+      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter)
     }
 
     resp_pattern <- sprintf("__zi_%s(.*)", resp)
     for (i in resp_pattern) {
-      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter, perl = TRUE)
+      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter)
     }
 
     resp_pattern <- sprintf("(sigma)(_%s)", resp)
     for (i in resp_pattern) {
-      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter, perl = TRUE)
+      out$Cleaned_Parameter <- gsub(pattern = i, "\\1", out$Cleaned_Parameter)
     }
   }
 
@@ -526,16 +526,16 @@ clean_parameters.mlm <- function(x, ...) {
   # clean fixed effects, conditional and zero-inflated
 
   out$Cleaned_Parameter <- gsub(pattern = "^b_(?!zi_)(.*)\\.(\\d)\\.$", "\\1[\\2]", out$Cleaned_Parameter, perl = TRUE)
-  out$Cleaned_Parameter <- gsub(pattern = "^b_zi_(.*)\\.(\\d)\\.$", "\\1[\\2]", out$Cleaned_Parameter, perl = TRUE)
+  out$Cleaned_Parameter <- gsub(pattern = "^b_zi_(.*)\\.(\\d)\\.$", "\\1[\\2]", out$Cleaned_Parameter)
   out$Cleaned_Parameter <- gsub(pattern = "^(b_|bs_|bsp_|bcs_)(?!zi_)(.*)", "\\2", out$Cleaned_Parameter, perl = TRUE)
-  out$Cleaned_Parameter <- gsub(pattern = "^(b_zi_|bs_zi_|bsp_zi_|bcs_zi_)(.*)", "\\2", out$Cleaned_Parameter, perl = TRUE) # nolint
+  out$Cleaned_Parameter <- gsub(pattern = "^(b_zi_|bs_zi_|bsp_zi_|bcs_zi_)(.*)", "\\2", out$Cleaned_Parameter) # nolint
 
   # correlation and sd
 
   cor_sd <- grepl("(sd_|cor_)(.*)", out$Cleaned_Parameter)
   if (any(cor_sd)) {
-    out$Cleaned_Parameter[cor_sd] <- gsub("^(sd_|cor_)(.*?)__(.*)", "\\3", out$Parameter[cor_sd], perl = TRUE)
-    out$Group[cor_sd] <- paste("SD/Cor:", gsub("^(sd_|cor_)(.*?)__(.*)", "\\2", out$Parameter[cor_sd], perl = TRUE))
+    out$Cleaned_Parameter[cor_sd] <- gsub("^(sd_|cor_)(.*?)__(.*)", "\\3", out$Parameter[cor_sd])
+    out$Group[cor_sd] <- paste("SD/Cor:", gsub("^(sd_|cor_)(.*?)__(.*)", "\\2", out$Parameter[cor_sd]))
     # replace "__" by "~"
     cor_only <- startsWith(out$Parameter[cor_sd], "cor_")
     if (any(cor_only)) {
@@ -645,14 +645,14 @@ clean_parameters.mlm <- function(x, ...) {
   cor_sd <- startsWith(out$Cleaned_Parameter, "Sigma[")
 
   if (any(cor_sd)) {
-    parm1 <- gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\2", out$Parameter[cor_sd], perl = TRUE)
-    parm2 <- gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\3", out$Parameter[cor_sd], perl = TRUE)
+    parm1 <- gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\2", out$Parameter[cor_sd])
+    parm2 <- gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\3", out$Parameter[cor_sd])
     out$Cleaned_Parameter[which(cor_sd)] <- parm1
     rand_cor <- parm1 != parm2
     if (any(rand_cor)) {
       out$Cleaned_Parameter[which(cor_sd)[rand_cor]] <- paste0(parm1[rand_cor], " ~ ", parm2[rand_cor])
     }
-    out$Group[cor_sd] <- paste("Var/Cov:", gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\1", out$Parameter[cor_sd], perl = TRUE))
+    out$Group[cor_sd] <- paste("Var/Cov:", gsub("^Sigma\\[(.*):(.*),(.*)\\]", "\\1", out$Parameter[cor_sd]))
   }
 
 
diff --git a/R/find_parameters_bayesian.R b/R/find_parameters_bayesian.R
index 393a623ce..4c1573412 100644
--- a/R/find_parameters_bayesian.R
+++ b/R/find_parameters_bayesian.R
@@ -225,7 +225,7 @@ find_parameters.brmsfit <- function(x,
 
   # remove redundant columns. These seem to be new since brms 2.16?
   pattern <- "^[A-z]_\\d\\.\\d\\.(.*)"
-  fe <- fe[!grepl(pattern, fe, perl = TRUE)]
+  fe <- fe[!grepl(pattern, fe)]
 
   is_mv <- NULL
 
@@ -233,21 +233,21 @@ find_parameters.brmsfit <- function(x,
   fe <- fe[!startsWith(fe, "Intercept")]
 
   cond <- fe[grepl("^(b_|bs_|bsp_|bcs_)(?!zi_)(.*)", fe, perl = TRUE)]
-  zi <- fe[grepl("^(b_zi_|bs_zi_|bsp_zi_|bcs_zi_)", fe, perl = TRUE)]
+  zi <- fe[grepl("^(b_zi_|bs_zi_|bsp_zi_|bcs_zi_)", fe)]
   rand <- fe[grepl("(?!.*__(zi|sigma|beta))(?=.*^r_)", fe, perl = TRUE) & !startsWith(fe, "prior_")]
-  randzi <- fe[grepl("^r_(.*__zi)", fe, perl = TRUE)]
+  randzi <- fe[grepl("^r_(.*__zi)", fe)]
   rand_sd <- fe[grepl("(?!.*_zi)(?=.*^sd_)", fe, perl = TRUE)]
-  randzi_sd <- fe[grepl("^sd_(.*_zi)", fe, perl = TRUE)]
+  randzi_sd <- fe[grepl("^sd_(.*_zi)", fe)]
   rand_cor <- fe[grepl("(?!.*_zi)(?=.*^cor_)", fe, perl = TRUE)]
-  randzi_cor <- fe[grepl("^cor_(.*_zi)", fe, perl = TRUE)]
+  randzi_cor <- fe[grepl("^cor_(.*_zi)", fe)]
   simo <- fe[startsWith(fe, "simo_")]
   car_struc <- fe[fe %in% c("car", "sdcar")]
   smooth_terms <- fe[startsWith(fe, "sds_")]
   priors <- fe[startsWith(fe, "prior_")]
   sigma_param <- fe[startsWith(fe, "sigma_") | grepl("sigma", fe, fixed = TRUE)]
-  randsigma <- fe[grepl("^r_(.*__sigma)", fe, perl = TRUE)]
+  randsigma <- fe[grepl("^r_(.*__sigma)", fe)]
   fixed_beta <- fe[grepl("beta", fe, fixed = TRUE)]
-  rand_beta <- fe[grepl("^r_(.*__beta)", fe, perl = TRUE)]
+  rand_beta <- fe[grepl("^r_(.*__beta)", fe)]
   mix <- fe[grepl("mix", fe, fixed = TRUE)]
   shiftprop <- fe[grepl("shiftprop", fe, fixed = TRUE)]
   dispersion <- fe[grepl("dispersion", fe, fixed = TRUE)]
diff --git a/R/helper_functions.R b/R/helper_functions.R
index 5a5f5b5ff..4ef896ca1 100644
--- a/R/helper_functions.R
+++ b/R/helper_functions.R
@@ -364,28 +364,13 @@
 
 
 .grep_zi_smoothers <- function(x) {
-  grepl("^(s\\.\\d\\()", x, perl = TRUE) |
-    grepl("^(gam::s\\.\\d\\()", x, perl = TRUE) |
-    grepl("^(mgcv::s\\.\\d\\()", x, perl = TRUE)
+  # this one captures smoothers in zi- or mv-models from gam
+  grepl("^(s\\.\\d\\()", x) | grepl("^(gam::s\\.\\d\\()", x) | grepl("^(mgcv::s\\.\\d\\()", x)
 }
 
 
 .grep_non_smoothers <- function(x) {
-  !startsWith(x, "s(") &
-    # this one captures smoothers in zi- or mv-models from gam
-    grepl("^(?!(s\\.\\d\\())", x, perl = TRUE) &
-    !startsWith(x, "ti(") &
-    !startsWith(x, "te(") &
-    !startsWith(x, "t2(") &
-    !startsWith(x, "gam::s(") &
-    !startsWith(x, "VGAM::s(") &
-    !startsWith(x, "mgcv::s(") &
-    !startsWith(x, "mgcv::ti(") &
-    !startsWith(x, "mgcv::t2(") &
-    !startsWith(x, "mgcv::te(") &
-    !startsWith(x, "brms::s(") &
-    !startsWith(x, "brms::t2") &
-    !startsWith(x, "smooth_sd[")
+  !.grep_smoothers(x) & !.grep_zi_smoothers(x)
 }
 
 
diff --git a/R/utilities.R b/R/utilities.R
index 96b0dea3c..18c5fbd80 100644
--- a/R/utilities.R
+++ b/R/utilities.R
@@ -46,7 +46,7 @@ trim_ws <- function(x, ...) {
 
 #' @export
 trim_ws.default <- function(x, ...) {
-  gsub("^\\s+|\\s+$", "", x, perl = TRUE, useBytes = TRUE)
+  gsub("^\\s+|\\s+$", "", x, useBytes = TRUE)
 }
 
 #' @rdname trim_ws