diff --git a/Sources/ComplexModule/Complex+Codable.swift b/Sources/ComplexModule/Complex+Codable.swift
index f7f094f7..c233cb7c 100644
--- a/Sources/ComplexModule/Complex+Codable.swift
+++ b/Sources/ComplexModule/Complex+Codable.swift
@@ -12,6 +12,9 @@
 import RealModule
 
 // FloatingPoint does not refine Codable, so this is a conditional conformance.
+#if compiler(>=6.0)
+@_unavailableInEmbedded
+#endif
 extension Complex: Decodable where RealType: Decodable {
   public init(from decoder: Decoder) throws {
     var unkeyedContainer = try decoder.unkeyedContainer()
@@ -21,6 +24,9 @@ extension Complex: Decodable where RealType: Decodable {
   }
 }
 
+#if compiler(>=6.0)
+@_unavailableInEmbedded
+#endif
 extension Complex: Encodable where RealType: Encodable {
   public func encode(to encoder: Encoder) throws {
     var unkeyedContainer = encoder.unkeyedContainer()
diff --git a/Sources/ComplexModule/Complex+StringConvertible.swift b/Sources/ComplexModule/Complex+StringConvertible.swift
index 85e7f781..1c88b5b3 100644
--- a/Sources/ComplexModule/Complex+StringConvertible.swift
+++ b/Sources/ComplexModule/Complex+StringConvertible.swift
@@ -16,6 +16,9 @@ extension Complex: CustomStringConvertible {
   }
 }
 
+#if compiler(>=6.0)
+@_unavailableInEmbedded
+#endif
 extension Complex: CustomDebugStringConvertible {
   public var debugDescription: String {
     "Complex<\(RealType.self)>(\(String(reflecting: x)), \(String(reflecting: y)))"