diff --git a/Sources/CodexBar/Date+RelativeDescription.swift b/Sources/CodexBar/Date+RelativeDescription.swift
index 7356f96710..cb3c4f59e5 100644
--- a/Sources/CodexBar/Date+RelativeDescription.swift
+++ b/Sources/CodexBar/Date+RelativeDescription.swift
@@ -4,6 +4,7 @@ enum RelativeTimeFormatters {
     @MainActor
     static let full: RelativeDateTimeFormatter = {
         let formatter = RelativeDateTimeFormatter()
+        formatter.locale = Locale(identifier: "en_US")
         formatter.unitsStyle = .full
         return formatter
     }()
diff --git a/Sources/CodexBar/PreferencesGeneralPane.swift b/Sources/CodexBar/PreferencesGeneralPane.swift
index 39a95a55ff..e5bce6ffe1 100644
--- a/Sources/CodexBar/PreferencesGeneralPane.swift
+++ b/Sources/CodexBar/PreferencesGeneralPane.swift
@@ -152,6 +152,7 @@ struct GeneralPane: View {
         }
         if let lastAttempt = self.store.tokenLastAttemptAt(for: provider) {
             let rel = RelativeDateTimeFormatter()
+            rel.locale = Locale(identifier: "en_US")
             rel.unitsStyle = .abbreviated
             let when = rel.localizedString(for: lastAttempt, relativeTo: Date())
             return Text("\(name): last attempt \(when)")
diff --git a/Sources/CodexBarCore/Providers/Augment/AugmentStatusProbe.swift b/Sources/CodexBarCore/Providers/Augment/AugmentStatusProbe.swift
index 82bf0fdd14..7c8e6bc7c8 100644
--- a/Sources/CodexBarCore/Providers/Augment/AugmentStatusProbe.swift
+++ b/Sources/CodexBarCore/Providers/Augment/AugmentStatusProbe.swift
@@ -226,6 +226,7 @@ public struct AugmentStatusSnapshot: Sendable {
 
     private static func formatResetDate(_ date: Date) -> String {
         let formatter = RelativeDateTimeFormatter()
+        formatter.locale = Locale(identifier: "en_US")
         formatter.unitsStyle = .full
         return formatter.localizedString(for: date, relativeTo: Date())
     }
diff --git a/Sources/CodexBarCore/UsageFormatter.swift b/Sources/CodexBarCore/UsageFormatter.swift
index 7f7dbae5aa..4b0ba1a8ad 100644
--- a/Sources/CodexBarCore/UsageFormatter.swift
+++ b/Sources/CodexBarCore/UsageFormatter.swift
@@ -76,6 +76,7 @@ public enum UsageFormatter {
         if let hours = Calendar.current.dateComponents([.hour], from: date, to: now).hour, hours < 24 {
             #if os(macOS)
             let rel = RelativeDateTimeFormatter()
+            rel.locale = Locale(identifier: "en_US")
             rel.unitsStyle = .abbreviated
             return "Updated \(rel.localizedString(for: date, relativeTo: now))"
             #else
diff --git a/Sources/CodexBarWidget/CodexBarWidgetViews.swift b/Sources/CodexBarWidget/CodexBarWidgetViews.swift
index 9944d39d80..614103b677 100644
--- a/Sources/CodexBarWidget/CodexBarWidgetViews.swift
+++ b/Sources/CodexBarWidget/CodexBarWidgetViews.swift
@@ -701,6 +701,7 @@ enum WidgetFormat {
 
     static func relativeDate(_ date: Date) -> String {
         let formatter = RelativeDateTimeFormatter()
+        formatter.locale = Locale(identifier: "en_US")
         formatter.unitsStyle = .short
         return formatter.localizedString(for: date, relativeTo: Date())
     }
diff --git a/Tests/CodexBarTests/UsageFormatterTests.swift b/Tests/CodexBarTests/UsageFormatterTests.swift
index 1358beedf5..15cd689944 100644
--- a/Tests/CodexBarTests/UsageFormatterTests.swift
+++ b/Tests/CodexBarTests/UsageFormatterTests.swift
@@ -21,9 +21,11 @@ struct UsageFormatterTests {
         let now = Date()
         let fiveHoursAgo = now.addingTimeInterval(-5 * 3600)
         let text = UsageFormatter.updatedString(from: fiveHoursAgo, now: now)
-        #expect(text.contains("Updated"))
-        // Check for relative time format (varies by locale: "ago" in English, "전" in Korean, etc.)
-        #expect(text.contains("5") || text.lowercased().contains("hour") || text.contains("시간"))
+        #expect(text.hasPrefix("Updated "))
+        // Output must stay in English regardless of the host system locale,
+        // matching the surrounding hardcoded English UI labels.
+        #expect(text.contains("5"))
+        #expect(text.lowercased().contains("ago"))
     }
 
     @Test