diff --git a/R/structural.properties.R b/R/structural.properties.R
index ca1029e1420..30cb7d930d9 100644
--- a/R/structural.properties.R
+++ b/R/structural.properties.R
@@ -2140,14 +2140,11 @@ bfs <- function(
   ensure_igraph(graph)
 
   if (lifecycle::is_present(neimode)) {
-    lifecycle::deprecate_warn(
+    lifecycle::deprecate_stop(
       "1.3.0",
       "bfs(neimode)",
       "bfs(mode)"
     )
-    if (missing(mode)) {
-      mode <- neimode
-    }
   }
 
   if (length(root) == 1) {
@@ -2315,14 +2312,11 @@ dfs <- function(graph, root, mode = c("out", "in", "all", "total"),
                 rho = parent.frame(), neimode = deprecated()) {
   ensure_igraph(graph)
   if (lifecycle::is_present(neimode)) {
-    lifecycle::deprecate_warn(
+    lifecycle::deprecate_stop(
       "1.3.0",
       "dfs(neimode)",
       "dfs(mode)"
     )
-    if (missing(mode)) {
-      mode <- neimode
-    }
   }
 
   root <- as_igraph_vs(graph, root) - 1
diff --git a/tests/testthat/_snaps/structural.properties.md b/tests/testthat/_snaps/structural.properties.md
index d8f926aeba1..55f08216249 100644
--- a/tests/testthat/_snaps/structural.properties.md
+++ b/tests/testthat/_snaps/structural.properties.md
@@ -3,8 +3,8 @@
     Code
       d <- dfs(g, root = 2, unreachable = FALSE, neimode = "out")
     Condition
-      Warning:
-      The `neimode` argument of `dfs()` is deprecated as of igraph 1.3.0.
+      Error:
+      ! The `neimode` argument of `dfs()` was deprecated in igraph 1.3.0 and is now defunct.
       i Please use the `mode` argument instead.
 
 ---
@@ -13,8 +13,8 @@
       b <- bfs(g, root = 2, neimode = "out", unreachable = FALSE, order = TRUE, rank = TRUE,
         father = TRUE, pred = TRUE, succ = TRUE, dist = TRUE)
     Condition
-      Warning:
-      The `neimode` argument of `bfs()` is deprecated as of igraph 1.3.0.
+      Error:
+      ! The `neimode` argument of `bfs()` was deprecated in igraph 1.3.0 and is now defunct.
       i Please use the `mode` argument instead.
 
 # bfs() works
diff --git a/tests/testthat/test-structural.properties.R b/tests/testthat/test-structural.properties.R
index 15089e98d3f..de12134cf12 100644
--- a/tests/testthat/test-structural.properties.R
+++ b/tests/testthat/test-structural.properties.R
@@ -15,7 +15,7 @@ test_that("dfs() does not pad order", {
 test_that("bfs() deprecated argument", {
   g <- make_star(3)
 
-  expect_snapshot({
+  expect_snapshot(error = TRUE, {
     d <- dfs(
       g,
       root = 2,
@@ -199,7 +199,7 @@ test_that("bfs() works", {
 test_that("bfs() deprecated argument", {
   g <- graph_from_literal(a - +b - +c, z - +a, d)
 
-  expect_snapshot({
+  expect_snapshot(error = TRUE, {
     b <- bfs(
       g,
       root = 2,