diff --git a/R/adjust-equivocal-zone.R b/R/adjust-equivocal-zone.R
index 829fade..5286e91 100644
--- a/R/adjust-equivocal-zone.R
+++ b/R/adjust-equivocal-zone.R
@@ -9,6 +9,8 @@
 #' @param value A numeric value (between zero and 1/2) or [hardhat::tune()]. The
 #' value is the size of the buffer around the threshold.
 #' @param threshold A numeric value (between zero and one) or [hardhat::tune()].
+#' Defaults to `adjust_probability_threshold(threshold)` if previously set
+#' in `x`, or `1 / 2` if not.
 #'
 #' @section Data Usage:
 #' This adjustment doesn't require estimation and, as such, the same data that's
@@ -56,16 +58,14 @@
 #' # adjust hard class predictions
 #' predict(tlr_fit, two_class_example) %>% count(predicted)
 #' @export
-adjust_equivocal_zone <- function(x, value = 0.1, threshold = 1 / 2) {
+adjust_equivocal_zone <- function(x, value = 0.1, threshold = NULL) {
   validate_probably_available()
 
   check_tailor(x)
+  threshold <- infer_threshold(x = x, threshold = threshold)
   if (!is_tune(value)) {
     check_number_decimal(value, min = 0, max = 1 / 2)
   }
-  if (!is_tune(threshold)) {
-    check_number_decimal(threshold, min = 10^-10, max = 1 - 10^-10)
-  }
 
   adj <-
     new_adjustment(
@@ -151,3 +151,24 @@ tunable.equivocal_zone <- function(x, ...) {
     component_id = "equivocal_zone"
   )
 }
+
+infer_threshold <- function(x, threshold, call = caller_env()) {
+  if (!is.null(threshold) && !is_tune(threshold)) {
+    check_number_decimal(threshold, min = 10^-10, max = 1 - 10^-10, call = call)
+    return(threshold)
+  }
+
+  if (is_tune(threshold)) {
+    return(threshold)
+  }
+
+  # use `map() %>% unlist()` rather than `map_dbl` to handle NULLs
+  thresholds <- purrr::map(x$adjustments, purrr::pluck, "arguments", "threshold")
+  thresholds <- unlist(thresholds)
+
+  if (!is.null(thresholds)) {
+    return(thresholds[length(thresholds)])
+  }
+
+  1 / 2
+}
diff --git a/man/adjust_equivocal_zone.Rd b/man/adjust_equivocal_zone.Rd
index 42f5476..abb554b 100644
--- a/man/adjust_equivocal_zone.Rd
+++ b/man/adjust_equivocal_zone.Rd
@@ -4,7 +4,7 @@
 \alias{adjust_equivocal_zone}
 \title{Apply an equivocal zone to a binary classification model.}
 \usage{
-adjust_equivocal_zone(x, value = 0.1, threshold = 1/2)
+adjust_equivocal_zone(x, value = 0.1, threshold = NULL)
 }
 \arguments{
 \item{x}{A \code{\link[=tailor]{tailor()}}.}
@@ -12,7 +12,9 @@ adjust_equivocal_zone(x, value = 0.1, threshold = 1/2)
 \item{value}{A numeric value (between zero and 1/2) or \code{\link[hardhat:tune]{hardhat::tune()}}. The
 value is the size of the buffer around the threshold.}
 
-\item{threshold}{A numeric value (between zero and one) or \code{\link[hardhat:tune]{hardhat::tune()}}.}
+\item{threshold}{A numeric value (between zero and one) or \code{\link[hardhat:tune]{hardhat::tune()}}.
+Defaults to \code{adjust_probability_threshold(threshold)} if previously set
+in \code{x}, or \code{1 / 2} if not.}
 }
 \description{
 Equivocal zones describe intervals of predicted probabilities that are deemed
diff --git a/tests/testthat/test-adjust-equivocal-zone.R b/tests/testthat/test-adjust-equivocal-zone.R
index 5bae335..e2d0835 100644
--- a/tests/testthat/test-adjust-equivocal-zone.R
+++ b/tests/testthat/test-adjust-equivocal-zone.R
@@ -72,3 +72,37 @@ test_that("tunable", {
     c("name", "call_info", "source", "component", "component_id")
   )
 })
+
+test_that("adjust_equivocal_zone inherits previously set threshold", {
+  # previously set
+  tlr <-
+    tailor() %>%
+    adjust_probability_threshold(threshold = .4) %>%
+    adjust_equivocal_zone(value = .2)
+
+  expect_equal(tlr$adjustments[[2]]$arguments$threshold, .4)
+
+  # not previously set, defualts to 1 / 2
+  tlr <-
+    tailor() %>%
+    adjust_equivocal_zone(value = .2)
+
+  expect_equal(tlr$adjustments[[1]]$arguments$threshold, .5)
+
+  # previously set, among other things
+  tlr <-
+    tailor() %>%
+    adjust_predictions_custom(.pred = identity(.pred)) %>%
+    adjust_probability_threshold(threshold = .4) %>%
+    adjust_equivocal_zone(value = .2)
+
+  expect_equal(tlr$adjustments[[3]]$arguments$threshold, .4)
+
+  # not previously set, but other stuff happened
+  tlr <-
+    tailor() %>%
+    adjust_predictions_custom(.pred = identity(.pred)) %>%
+    adjust_equivocal_zone(value = .2)
+
+  expect_equal(tlr$adjustments[[2]]$arguments$threshold, .5)
+})