diff --git a/Sources/FoundationEssentials/Calendar/Calendar.swift b/Sources/FoundationEssentials/Calendar/Calendar.swift
index 6e3385b36..95fc45cc6 100644
--- a/Sources/FoundationEssentials/Calendar/Calendar.swift
+++ b/Sources/FoundationEssentials/Calendar/Calendar.swift
@@ -92,9 +92,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
         @available(FoundationPreview 6.2, *)
         case dangi
         
-        @available(FoundationPreview 6.2, *)
-        case thai
-        
         @available(FoundationPreview 6.2, *)
         case vietnamese
 
@@ -135,7 +132,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
             case "telugu": self = .telugu
             case "vikram": self = .vikram
             case "dangi": self = .dangi
-            case "thai": self = .thai
             case "vietnamese": self = .vietnamese
             default: return nil
             }
@@ -169,7 +165,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
             case .telugu: return "telugu"
             case .vikram: return "vikram"
             case .dangi: return "dangi"
-            case .thai: return "thai"
             case .vietnamese: return "vietnamese"
             }
         }
@@ -203,7 +198,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
             case .telugu: return "telugu"
             case .vikram: return "vikram"
             case .dangi: return "dangi"
-            case .thai: return "thai"
             case .vietnamese: return "vietnamese"
             }
         }
@@ -1404,8 +1398,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
             return .vikram
         case .dangi: 
             return .dangi
-        case .thai:
-            return .thai
         case .vietnamese:
             return .vietnamese
         }
@@ -1465,8 +1457,6 @@ public struct Calendar : Hashable, Equatable, Sendable {
             return .vikram
         case .dangi:
             return .dangi
-        case .thai:
-            return .thai
         case .vietnamese:
             return .vietnamese
         default:
diff --git a/Sources/FoundationInternationalization/Calendar/Calendar_ICU.swift b/Sources/FoundationInternationalization/Calendar/Calendar_ICU.swift
index eb1d9a6a9..3875ac3c9 100644
--- a/Sources/FoundationInternationalization/Calendar/Calendar_ICU.swift
+++ b/Sources/FoundationInternationalization/Calendar/Calendar_ICU.swift
@@ -1468,8 +1468,6 @@ internal final class _CalendarICU: _CalendarProtocol, @unchecked Sendable {
                 return Date(timeIntervalSinceReferenceDate: -60645542400.0)
             case .dangi:
                 fallthrough
-            case .thai:
-                fallthrough
             case .vietnamese:
                 // TODO: This is copied from `.chinese` and needs to be revisited for each new calendar.
                 if time < -146325744000.0 { return nil }
@@ -1590,8 +1588,6 @@ internal final class _CalendarICU: _CalendarProtocol, @unchecked Sendable {
                 return DateInterval(start: Date(timeIntervalSinceReferenceDate: -60645542400.0), duration: inf_ti)
             case .dangi:
                 fallthrough
-            case .thai:
-                fallthrough
             case .vietnamese:
                 // TODO: This is copied from `.chinese` and needs to be revisited for each new calendar.
                 if time < -146325744000.0 { return nil }