diff --git a/R/csv.R b/R/csv.R
index 8ac91393..a091fc19 100644
--- a/R/csv.R
+++ b/R/csv.R
@@ -697,7 +697,13 @@ read_csv_metadata <- function(csv_file) {
   for (line in metadata[[1]]) {
     if (!startsWith(line, "#") && is.null(csv_file_info[["variables"]])) {
       # if no # at the start of line, the line is the CSV header
-      all_names <- strsplit(line, ",")[[1]]
+      header_dt <- data.table::fread(
+        text = line,
+        header = FALSE,
+        check.names = FALSE,
+        data.table = FALSE
+      )
+      all_names <- as.character(header_dt[1, ])
       if (all(csv_file_info$algorithm != "fixed_param")) {
         csv_file_info[["sampler_diagnostics"]] <- all_names[endsWith(all_names, "__")]
         csv_file_info[["sampler_diagnostics"]] <- csv_file_info[["sampler_diagnostics"]][!(csv_file_info[["sampler_diagnostics"]] %in% c("lp__", "log_p__", "log_g__", "log_q__"))]
@@ -915,8 +921,10 @@ check_csv_metadata_matches <- function(csv_metadata) {
   NULL
 }
 
-# convert names like beta.1.1 to beta[1,1]
+# convert names like beta.1.1 or beta(1,1) to beta[1,1]
 repair_variable_names <- function(names) {
+  names <- sub("\\(", "[", names)
+  names <- gsub("\\)", "", names)
   names <- sub("\\.", "[", names)
   names <- gsub("\\.", ",", names)
   names[grep("\\[", names)] <-
@@ -983,7 +991,9 @@ variable_dims <- function(variable_names = NULL) {
   uniq_variable_names <- unique(gsub("\\[.*\\]", "", variable_names))
   var_names <- gsub("\\]", "", variable_names)
   for (var in uniq_variable_names) {
-    pattern <- paste0("^", var, "\\[")
+    # escape regex symbols
+    esc_var <- gsub("([][{}()+*?.^$|\\\\])", "\\\\\\1", var)
+    pattern <- paste0("^", esc_var, "\\[")
     var_indices <- var_names[grep(pattern, var_names)]
     var_indices <- gsub(pattern, "", var_indices)
     if (length(var_indices)) {
diff --git a/tests/testthat/test-csv.R b/tests/testthat/test-csv.R
index dc678a6b..827c3cc9 100644
--- a/tests/testthat/test-csv.R
+++ b/tests/testthat/test-csv.R
@@ -95,6 +95,19 @@ test_that("read_cmdstan_csv() fails with the no params listed", {
                "Supplied CSV file does not contain any variable names or data!")
 })
 
+test_that("variable_dims works for standard Stan names", {
+  vars <- c("beta[1]", "beta[2]", "beta[3]", "sigma")
+  dims <- variable_dims(vars)
+  expect_equal(dims$beta, 3)
+  expect_equal(dims$sigma, 1)
+})
+
+test_that("variable_dims handles names with regex metacharacters", {
+  vars <- c('SIGMA(1,1)[1,2]', 'SIGMA(1,1)[2,2]')
+  dims <- variable_dims(vars)
+  expect_equal(dims[["SIGMA(1,1)"]], c(2, 2))
+})
+
 test_that("read_cmdstan_csv() matches utils::read.csv", {
   csv_files <- c(test_path("resources", "csv", "model1-1-warmup.csv"),
                  test_path("resources", "csv", "model1-2-warmup.csv"))
@@ -896,3 +909,56 @@ test_that("read_cmdstan_csv() works with tilde expansion", {
   tildified_path <- file.path("~", fs::path_rel(full_path, "~"))
   expect_no_error(read_cmdstan_csv(tildified_path))
 })
+
+test_that("as_cmdstan_fit handles parameter names with parentheses and indices", {
+  skip_on_cran()
+
+  csv_file <- withr::local_tempfile(fileext = ".csv")
+  lines <- c(
+    "# model = norm_model",
+    "# method = sample (Default)",
+    "# id = 1",
+    "# thin = 1",
+    "# save_warmup = 0",
+    'lp__,accept_stat__,stepsize__,treedepth__,n_leapfrog__,divergent__,energy__,"Sigma(1,1)","Sigma(1,2)","Sigma(2,1)","Sigma(2,2)"',
+    "-65.951579,0.92571393,0.77752825,3,7,0,67.391073,0.2808549,-0.95718644,0.080662461,0.58814086",
+    "-66.417297,0.89632515,0.77752825,2,3,0,68.026905,0.3014893,-0.97834703,0.069719538,0.89573157"
+  )
+  writeLines(lines, csv_file)
+
+  fit <- as_cmdstan_fit(csv_file, check_diagnostics = FALSE)
+
+  vars <- posterior::variables(fit$draws())
+  expect_true(all(
+    c("Sigma[1,1]", "Sigma[1,2]", "Sigma[2,1]", "Sigma[2,2]") %in% vars
+  ))
+
+  dims <- fit$metadata()$stan_variable_sizes
+  expect_equal(dims[["Sigma"]], c(2, 2))
+})
+
+test_that("as_cmdstan_fit handles variable names with parentheses", {
+  skip_on_cran()
+  csv_file <- withr::local_tempfile(fileext = ".csv")
+  writeLines(c(
+    "# model = norm_model",
+    "# method = sample (Default)",
+    "# id = 1",
+    "# thin = 1",
+    "# save_warmup = 0",
+    "THETA4,SIGMA(1,1)",
+    "2.00000E+00,2.00000E+00",
+    "2.00000E+00,2.00000E+00"
+  ), con = csv_file)
+
+  expect_no_error({
+    fit <- as_cmdstan_fit(csv_file, check_diagnostics = FALSE, format = "draws_matrix")
+  })
+
+  draws <- fit$draws()
+  vars  <- posterior::variables(draws)
+
+  expect_equal(posterior::ndraws(draws), 2L)
+  expect_true(any(grepl("THETA4", vars)))
+  expect_true(any(grepl("SIGMA", vars)))
+})