diff --git a/DESCRIPTION b/DESCRIPTION
index 8f37c85cc..77a645af1 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Type: Package
 Package: parameters
 Title: Processing of Model Parameters
-Version: 0.29.3.2
+Version: 0.29.3.3
 Authors@R:
     c(person(given = "Daniel",
              family = "Lüdecke",
diff --git a/NEWS.md b/NEWS.md
index 1d7f07726..f14831947 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -7,6 +7,9 @@
 
 ## Bug fixes
 
+* `model_parameters(..., effects = "grouplevel")` now formats categorical
+  random-slope labels consistently across all grouping levels.
+
 * `standard_error()` and hence `model_parameters()` returned wrong (recycled)
   standard errors for models of class `glmmTMB` fitted with the new `ordinal()`
   family, because the thresholds are not part of the summary coefficient table.
diff --git a/R/format_parameters.R b/R/format_parameters.R
index 9886a5af6..ffbec0393 100644
--- a/R/format_parameters.R
+++ b/R/format_parameters.R
@@ -593,7 +593,9 @@ format_parameters.parameters_model <- function(model, ...) {
   # missing labels return original parameter name (e.g., variance components in mixed models)
   out <- stats::setNames(params$Parameter, params$Parameter)
   pretty_labels <- pretty_labels[names(pretty_labels) %in% params$Parameter]
-  out[match(names(pretty_labels), params$Parameter)] <- pretty_labels
+  label_idx <- match(params$Parameter, names(pretty_labels))
+  has_label <- !is.na(label_idx)
+  out[has_label] <- pretty_labels[label_idx[has_label]]
 
   out
 }
diff --git a/tests/testthat/test-glmmTMB.R b/tests/testthat/test-glmmTMB.R
index 9ddec0b3c..1cb7b99a2 100644
--- a/tests/testthat/test-glmmTMB.R
+++ b/tests/testthat/test-glmmTMB.R
@@ -855,12 +855,12 @@ withr::with_options(list(parameters_exponentiate = FALSE), {
         camper1 = "camper [1]",
         `(Intercept)` = "(Intercept)",
         child = "child",
-        camper1 = "camper1", # nolint
+        camper1 = "camper [1]",
         `SD (Intercept)` = "SD (Intercept)",
         `SD (xb)` = "SD (xb)",
         `Cor (Intercept~xb)` = "Cor (Intercept~xb)",
         `SD (Intercept)` = "SD (Intercept)",
-        `SD (zg)` = "SD (zg)", # nolint
+        `SD (zg)` = "SD (zg)",
         `Cor (Intercept~zg)` = "Cor (Intercept~zg)"
       )
     )
diff --git a/tests/testthat/test-model_parameters.mixed.R b/tests/testthat/test-model_parameters.mixed.R
index b2c992cdf..3e7aa6d5f 100644
--- a/tests/testthat/test-model_parameters.mixed.R
+++ b/tests/testthat/test-model_parameters.mixed.R
@@ -116,6 +116,20 @@ test_that("model_parameters.mixed-random, grouplevel", {
   expect_equal(params$Coefficient, c(0.1692, 0.0566, -0.2259), tolerance = 1e-2)
 })
 
+test_that("model_parameters.mixed-random, grouplevel factor labels", {
+  dat <- transform(lme4::sleepstudy, treatment = factor(ifelse(Days > 4, "1", "0")))
+  model <- lme4::lmer(Reaction ~ treatment + (1 + treatment | Subject), data = dat)
+  params <- model_parameters(model, effects = "grouplevel")
+  pretty_labels <- attr(params, "pretty_labels")
+  treatment_labels <- pretty_labels[grepl("^treatment", names(pretty_labels))]
+
+  expect_length(treatment_labels, length(unique(dat$Subject)))
+  expect_identical(
+    as.character(treatment_labels),
+    rep("treatment [1]", length(treatment_labels))
+  )
+})
+
 test_that("model_parameters.mixed-ran_pars", {
   params <- model_parameters(m1, effects = "random")
   expect_identical(c(nrow(params), ncol(params)), c(2L, 8L))