diff --git a/DESCRIPTION b/DESCRIPTION
index 90b9cf61..da2068b5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: gDRutils
 Type: Package
 Title: A package with helper functions for processing drug response data
-Version: 1.3.13
-Date: 2024-09-16
+Version: 1.3.14
+Date: 2024-10-03
 Authors@R: c(person("Bartosz", "Czech", role=c("aut"),
                    comment = c(ORCID = "0000-0002-9908-3007")),
              person("Arkadiusz", "Gladki", role=c("cre", "aut"), email="gladki.arkadiusz@gmail.com",
diff --git a/NEWS.md b/NEWS.md
index b0cd85c0..d6c0d80e 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,6 @@
+## gDRutils 1.3.14 - 2024-10-03
+* fixed issue in average_biological_replicated (fit_type)
+
 ## gDRutils 1.3.13 - 2024-09-16
 * add functions set_unique_cl_names_dt and set_unique_drug_names_dt
 
diff --git a/R/headers_list.R b/R/headers_list.R
index 995c035d..df09f265 100644
--- a/R/headers_list.R
+++ b/R/headers_list.R
@@ -191,8 +191,20 @@
       "GR50",
       "GEC50",
       "IC50",
-      "EC50"
-    )
+      "EC50",
+      "GR_xc50",
+      "RV_xc50",
+      "GR_ec50",
+      "RV_ec50"
+    ),
+    fit_type = c(
+      "fit_type",
+      "Fit Type",
+      "Fit Type RV",
+      "Fit Type GR",
+      "RV_fit_type",
+      "GR_fit_type"
+   )
   )
 }
 
diff --git a/R/utils.R b/R/utils.R
index 007a1cb7..85895572 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -433,6 +433,8 @@ geometric_mean <- function(x, fixed = TRUE, maxlog10Concentration = 1) {
 #' @param fixed Flag indicating whether to add a fix for -Inf in the geometric mean.
 #' @param geometric_average_fields Character vector of column names in \code{dt} 
 #' to take the geometric average of.
+#' @param fit_type_average_fields Character vector of column names in \code{dt} 
+#' that should be treated as a column with fit type data
 #' @param add_sd Flag indicating whether to add standard deviation and count columns.
 #' 
 #' @examples
@@ -449,8 +451,16 @@ average_biological_replicates_dt <- function(
     prettified = FALSE,
     fixed = TRUE,
     geometric_average_fields = get_header("metric_average_fields")$geometric_mean,
+    fit_type_average_fields = get_header("metric_average_fields")$fit_type,
     add_sd = FALSE) {
   
+  checkmate::assert_data_table(dt)
+  checkmate::assert_string(var)
+  checkmate::assert_flag(prettified)
+  checkmate::assert_character(geometric_average_fields)
+  checkmate::assert_character(fit_type_average_fields)
+  checkmate::assert_flag(add_sd)
+  
   data <- data.table::copy(dt)
   
   if (prettified) {
@@ -465,7 +475,8 @@ average_biological_replicates_dt <- function(
   
   average_fields <- setdiff(names(Filter(is.numeric, data)), c(unlist(pidfs), var, iso_cols))
   geometric_average_fields <- intersect(geometric_average_fields, names(dt))
-  group_by <- setdiff(names(data), c(average_fields, var, id_cols, "fit_type", "Fit Type"))
+  fit_type_average_fields <- intersect(fit_type_average_fields, names(dt))
+  group_by <- setdiff(names(data), c(average_fields, var, id_cols, fit_type_average_fields))
   
   if (add_sd) {
     # Calculate standard deviation for both average_fields and geometric_average_fields
diff --git a/man/average_biological_replicates_dt.Rd b/man/average_biological_replicates_dt.Rd
index 8f712fa6..ba726af1 100644
--- a/man/average_biological_replicates_dt.Rd
+++ b/man/average_biological_replicates_dt.Rd
@@ -10,6 +10,7 @@ average_biological_replicates_dt(
   prettified = FALSE,
   fixed = TRUE,
   geometric_average_fields = get_header("metric_average_fields")$geometric_mean,
+  fit_type_average_fields = get_header("metric_average_fields")$fit_type,
   add_sd = FALSE
 )
 }
@@ -25,6 +26,9 @@ average_biological_replicates_dt(
 \item{geometric_average_fields}{Character vector of column names in \code{dt}
 to take the geometric average of.}
 
+\item{fit_type_average_fields}{Character vector of column names in \code{dt}
+that should be treated as a column with fit type data}
+
 \item{add_sd}{Flag indicating whether to add standard deviation and count columns.}
 }
 \value{
diff --git a/tests/testthat/test-utils.R b/tests/testthat/test-utils.R
index 11f775fb..143fa9f4 100644
--- a/tests/testthat/test-utils.R
+++ b/tests/testthat/test-utils.R
@@ -223,6 +223,36 @@ test_that("average_biological_replicates_dt works as expected", {
   expect_equal(dim(avg_metrics_data2), c(40, 44))
   expect_equal(sum(grepl("_sd", names(avg_metrics_data2))), 15)
   expect_true("count" %in% names(avg_metrics_data2))
+  
+  # protection against regression
+  # fit_type correctly recognized in wide and long format
+  sdata <- get_synthetic_data("finalMAE_small")
+  smetrics_data <- convert_se_assay_to_dt(sdata[[1]], "Metrics")
+  tdata <- smetrics_data[1:8, ]
+  tdata$Gnumber <- tdata$Gnumber[1]
+  tdata$DrugName <- tdata$DrugName[1]
+  tdata$source_id <- paste0("DS", rep(1:4, each = 2))
+  tdata$fit_type <- letters[1:8]
+  
+  av1b <- average_biological_replicates_dt(tdata, var = "source_id")
+  av1f <- gDRutils::flatten(
+    av1b,
+    groups = c("normalization_type", "fit_source"),
+    wide_cols = gDRutils::get_header("response_metrics")
+  )
+  
+  av2f <- gDRutils::flatten(
+    tdata,
+    groups = c("normalization_type", "fit_source"),
+    wide_cols = gDRutils::get_header("response_metrics")
+  )
+  av2b <- average_biological_replicates_dt(av2f, var = "source_id")
+  expect_true(all.equal(av1f, av2b))
+  expect_true(nrow(av1f) == 1)
+  av1i <- average_biological_replicates_dt(tdata, var = "source_id", fit_type_average_fields = "bad_value")
+  expect_true(nrow(av1i) == 8)
+  
+  
 })
 
 test_that("get_duplicated_rows works as expected", {