diff --git a/Package.swift b/Package.swift
index 27ee3d2..a9f7326 100644
--- a/Package.swift
+++ b/Package.swift
@@ -3,7 +3,7 @@ import PackageDescription
 
 let package:Package = .init(
     name: "swift-hash",
-    platforms: [.macOS("13.3"), .iOS("16.4"), .tvOS("16.4"), .watchOS("9.4")],
+    platforms: [.macOS(.v10_15), .iOS(.v13), .tvOS(.v13), .watchOS(.v6)],
     products: [
         .library(name: "Base16",                targets: ["Base16"]),
         .library(name: "Base64",                targets: ["Base64"]),
diff --git a/Sources/InlineBuffer/InlineBuffer.swift b/Sources/InlineBuffer/InlineBuffer.swift
index d947b28..c56ee36 100644
--- a/Sources/InlineBuffer/InlineBuffer.swift
+++ b/Sources/InlineBuffer/InlineBuffer.swift
@@ -100,6 +100,7 @@ extension InlineBuffer:RandomAccessCollection, MutableCollection
         }
     }
 }
+@available(macOS 13.3, iOS 16.4, macCatalyst 16.4, tvOS 16.4, visionOS 1, watchOS 9.4, *)
 extension InlineBuffer:ExpressibleByIntegerLiteral
 {
     @inlinable public
@@ -153,18 +154,32 @@ extension InlineBuffer:CustomStringConvertible
     @inlinable public
     var description:String
     {
-        .init(unsafeUninitializedCapacity: 2 * self.count)
+        func hex(remainder:UInt8) -> UInt8
         {
-            func hex(remainder:UInt8) -> UInt8
+            (remainder < 10 ? 0x30 : 0x61 - 10) &+ remainder
+        }
+        if #available(macOS 11, iOS 14, macCatalyst 14, tvOS 14, visionOS 1, watchOS 7, *)
+        {
+            return .init(unsafeUninitializedCapacity: 2 * self.count)
             {
-                (remainder < 10 ? 0x30 : 0x61 - 10) &+ remainder
+                for (i, byte):(Int, UInt8) in self.enumerated()
+                {
+                    $0[2 * i    ] = hex(remainder: byte >> 4)
+                    $0[2 * i + 1] = hex(remainder: byte & 0x0f)
+                }
+                return 2 * self.count
             }
-            for (i, byte):(Int, UInt8) in self.enumerated()
+        }
+        else
+        {
+            var description:String = ""
+            description.reserveCapacity(2 * self.count)
+            for byte:UInt8 in self
             {
-                $0[2 * i    ] = hex(remainder: byte >> 4)
-                $0[2 * i + 1] = hex(remainder: byte & 0x0f)
+                description.append(Character.init(.init(hex(remainder: byte >> 4))))
+                description.append(Character.init(.init(hex(remainder: byte & 0x0f))))
             }
-            return 2 * self.count
+            return description
         }
     }
 }
diff --git a/Sources/MD5/MD5.swift b/Sources/MD5/MD5.swift
index cb9d4f5..66a2283 100644
--- a/Sources/MD5/MD5.swift
+++ b/Sources/MD5/MD5.swift
@@ -100,6 +100,7 @@ extension MD5:LosslessStringConvertible
         }
     }
 }
+@available(macOS 13.3, iOS 16.4, macCatalyst 16.4, tvOS 16.4, visionOS 1, watchOS 9.4, *)
 extension MD5:ExpressibleByIntegerLiteral
 {
     @inlinable public
diff --git a/Sources/MD5Tests/Main.swift b/Sources/MD5Tests/Main.swift
index 3c9a3c7..9282d5f 100644
--- a/Sources/MD5Tests/Main.swift
+++ b/Sources/MD5Tests/Main.swift
@@ -7,6 +7,20 @@ enum Main:TestMain, TestBattery
     static
     func run(tests:TestGroup)
     {
+        guard #available(
+            macOS 13.3,
+            iOS 16.4,
+            macCatalyst 16.4,
+            tvOS 16.4,
+            visionOS 1.0,
+            watchOS 9.4,
+            *
+        )
+        else
+        {
+            fatalError("MD5Tests requires macOS 13.3+, iOS 16.4+, tvOS 16.4+, visionOS 1.0+, or watchOS 9.4+")
+        }
+
         if  let tests:TestGroup = tests / "Strings"
         {
             let string:String   =   "d41d8cd98f00b204e9800998ecf8427e"
diff --git a/Sources/SHA1/SHA1.swift b/Sources/SHA1/SHA1.swift
index 1e180da..2b74299 100644
--- a/Sources/SHA1/SHA1.swift
+++ b/Sources/SHA1/SHA1.swift
@@ -83,6 +83,7 @@ extension SHA1:LosslessStringConvertible
         }
     }
 }
+@available(macOS 13.3, iOS 16.4, macCatalyst 16.4, tvOS 16.4, visionOS 1, watchOS 9.4, *)
 extension SHA1:ExpressibleByIntegerLiteral
 {
     @inlinable public