diff --git a/lib/command_duration.bash b/lib/command_duration.bash
index cd1d6636db..ec4d828d0c 100644
--- a/lib/command_duration.bash
+++ b/lib/command_duration.bash
@@ -2,12 +2,24 @@
 #
 # Functions for measuring and reporting how long a command takes to run.
 
-: "${COMMAND_DURATION_START_SECONDS:=${EPOCHREALTIME:-$SECONDS}}"
+# Get shell duration in decimal format regardless of runtime locale.
+# Notice: This function runs as a sub-shell - notice '(' vs '{'.
+function _shell_duration_en() (
+	# DFARREL You would think LC_NUMERIC would do it, but not working in my local
+	LC_ALL='en_US.UTF-8'
+	printf "%s" "${EPOCHREALTIME:-$SECONDS}"
+)
+
+: "${COMMAND_DURATION_START_SECONDS:=$(_shell_duration_en)}"
 : "${COMMAND_DURATION_ICON:=🕘}"
 : "${COMMAND_DURATION_MIN_SECONDS:=1}"
 
 function _command_duration_pre_exec() {
-	COMMAND_DURATION_START_SECONDS="${EPOCHREALTIME:-$SECONDS}"
+	COMMAND_DURATION_START_SECONDS="$(_shell_duration_en)"
+}
+
+function _command_duration_pre_cmd() {
+	COMMAND_DURATION_START_SECONDS=""
 }
 
 function _dynamic_clock_icon {
@@ -20,13 +32,15 @@ function _dynamic_clock_icon {
 
 function _command_duration() {
 	[[ -n "${BASH_IT_COMMAND_DURATION:-}" ]] || return
+	[[ -n "${COMMAND_DURATION_START_SECONDS:-}" ]] || return
 
 	local command_duration=0 command_start="${COMMAND_DURATION_START_SECONDS:-0}"
 	local -i minutes=0 seconds=0 deciseconds=0
 	local -i command_start_seconds="${command_start%.*}"
 	local -i command_start_deciseconds=$((10#${command_start##*.}))
 	command_start_deciseconds="${command_start_deciseconds:0:1}"
-	local current_time="${EPOCHREALTIME:-$SECONDS}"
+	local current_time
+	current_time="$(_shell_duration_en)"
 	local -i current_time_seconds="${current_time%.*}"
 	local -i current_time_deciseconds="$((10#${current_time##*.}))"
 	current_time_deciseconds="${current_time_deciseconds:0:1}"
@@ -59,3 +73,4 @@ function _command_duration() {
 }
 
 _bash_it_library_finalize_hook+=("safe_append_preexec '_command_duration_pre_exec'")
+_bash_it_library_finalize_hook+=("safe_append_prompt_command '_command_duration_pre_cmd'")
diff --git a/plugins/available/cmd-returned-notify.plugin.bash b/plugins/available/cmd-returned-notify.plugin.bash
index 88c07722df..e6d221faac 100644
--- a/plugins/available/cmd-returned-notify.plugin.bash
+++ b/plugins/available/cmd-returned-notify.plugin.bash
@@ -4,7 +4,8 @@ about-plugin 'Alert (BEL) when process ends after a threshold of seconds'
 
 function precmd_return_notification() {
 	local command_start="${COMMAND_DURATION_START_SECONDS:=0}"
-	local current_time="${EPOCHREALTIME:-$SECONDS}"
+	local current_time
+	current_time="$(_shell_duration_en)"
 	local -i command_duration="$((${current_time%.*} - ${command_start%.*}))"
 	if [[ "${command_duration}" -gt "${NOTIFY_IF_COMMAND_RETURNS_AFTER:-5}" ]]; then
 		printf '\a'
diff --git a/test/plugins/cmd-returned-notify.plugin.bats b/test/plugins/cmd-returned-notify.plugin.bats
index 04edad9582..a5ae591a51 100644
--- a/test/plugins/cmd-returned-notify.plugin.bats
+++ b/test/plugins/cmd-returned-notify.plugin.bats
@@ -9,7 +9,7 @@ function local_setup_file() {
 
 @test "plugins cmd-returned-notify: notify after elapsed time" {
 	export NOTIFY_IF_COMMAND_RETURNS_AFTER=0
-	export COMMAND_DURATION_START_SECONDS="${EPOCHREALTIME:-$SECONDS}"
+	export COMMAND_DURATION_START_SECONDS="$(_shell_duration_en)"
 	sleep 1
 	run precmd_return_notification
 	assert_success
@@ -18,7 +18,7 @@ function local_setup_file() {
 
 @test "plugins cmd-returned-notify: do not notify before elapsed time" {
 	export NOTIFY_IF_COMMAND_RETURNS_AFTER=10
-	export COMMAND_DURATION_START_SECONDS="${EPOCHREALTIME:-$SECONDS}"
+	export COMMAND_DURATION_START_SECONDS="$(_shell_duration_en)"
 	sleep 1
 	run precmd_return_notification
 	assert_success
@@ -34,7 +34,7 @@ function local_setup_file() {
 @test "lib command_duration: preexec set COMMAND_DURATION_START_SECONDS" {
 	export COMMAND_DURATION_START_SECONDS=
 	assert_equal "${COMMAND_DURATION_START_SECONDS}" ""
-	NOW="${EPOCHREALTIME:-$SECONDS}"
+	NOW="$(_shell_duration_en)"
 	_command_duration_pre_exec
 	# We need to make sure to account for nanoseconds...
 	assert_equal "${COMMAND_DURATION_START_SECONDS%.*}" "${NOW%.*}"