diff --git a/Package.swift b/Package.swift
index c4a2c00..7fa7f62 100644
--- a/Package.swift
+++ b/Package.swift
@@ -3,7 +3,7 @@ import PackageDescription
 
 let package:Package = .init(
     name: "swift-hash",
-    platforms: [.macOS(.v14), .iOS(.v17), .tvOS(.v17), .visionOS(.v1), .watchOS(.v10)],
+    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/MD5Tests/Hashing.swift b/Sources/MD5Tests/Hashing.swift
index 02db3fd..d70e473 100644
--- a/Sources/MD5Tests/Hashing.swift
+++ b/Sources/MD5Tests/Hashing.swift
@@ -5,39 +5,80 @@ import Testing
 @Suite
 struct Hashing
 {
-    @Test(arguments: [
-            (0xd41d8cd98f00b204e9800998ecf8427e, []),
-            (0x0cc175b9c0f1b6a831c399e269772661, [0x61]),
-            (0x900150983cd24fb0d6963f7d28e17f72, [0x61, 0x62, 0x63]),
-        ] as [(MD5, [UInt8])])
+    private
+    static var binary:[(MD5, [UInt8])]
+    {
+        if #available(
+            macOS 13.3,
+            macCatalyst 16.4,
+            iOS 16.4,
+            tvOS 16.4,
+            visionOS 1.0,
+            watchOS 9.4,
+            *)
+        {
+            [
+                (0xd41d8cd98f00b204e9800998ecf8427e, []),
+                (0x0cc175b9c0f1b6a831c399e269772661, [0x61]),
+                (0x900150983cd24fb0d6963f7d28e17f72, [0x61, 0x62, 0x63]),
+            ]
+        }
+        else
+        {
+            []
+        }
+    }
+
+    @Test(arguments: Self.binary)
     static func binary(_ test:(expected:MD5, input:[UInt8]))
     {
         let md5:MD5 = .init(hashing: test.input)
         #expect(md5 == test.expected)
     }
 
-    @Test(arguments: [
-            (
-                0xf96b697d7cb7938d525a2f31aaf161d0,
-                "message digest"
-            ),
-            (
-                0xc3fcd3d76192e4007dfb496cca67e13b,
-                "abcdefghijklmnopqrstuvwxyz"
-            ),
-            (
-                0xd174ab98d277d9f5a5611c2c9f419d9f,
-                """
-                ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
-                """
-            ),
-            (
-                0x57edf4a22be3c955ac49da2e2107b67a,
-                """
-                12345678901234567890123456789012345678901234567890123456789012345678901234567890
-                """
-            ),
-        ] as [(MD5, String)])
+    private
+    static var string:[(MD5, String)]
+    {
+        if #available(
+            macOS 13.3,
+            macCatalyst 16.4,
+            iOS 16.4,
+            tvOS 16.4,
+            visionOS 1.0,
+            watchOS 9.4,
+            *)
+        {
+            [
+                (
+                    0xf96b697d7cb7938d525a2f31aaf161d0,
+                    "message digest"
+                ),
+                (
+                    0xc3fcd3d76192e4007dfb496cca67e13b,
+                    "abcdefghijklmnopqrstuvwxyz"
+                ),
+                (
+                    0xd174ab98d277d9f5a5611c2c9f419d9f,
+                    """
+                    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
+                    """
+                ),
+                (
+                    0x57edf4a22be3c955ac49da2e2107b67a,
+                    """
+                    1234567890123456789012345678901234567890\
+                    1234567890123456789012345678901234567890
+                    """
+                ),
+            ]
+        }
+        else
+        {
+            []
+        }
+    }
+
+    @Test(arguments: Self.string)
     static func string(_ test:(expected:MD5, input:String))
     {
         let md5:MD5 = .init(hashing: test.input.utf8)
diff --git a/Sources/MD5Tests/ParsingAndFormatting.swift b/Sources/MD5Tests/ParsingAndFormatting.swift
index 5e5030c..3351812 100644
--- a/Sources/MD5Tests/ParsingAndFormatting.swift
+++ b/Sources/MD5Tests/ParsingAndFormatting.swift
@@ -7,11 +7,21 @@ struct ParsingAndFormatting
     @Test
     static func strings() throws
     {
-        let string:String = "d41d8cd98f00b204e9800998ecf8427e"
-        let hash:MD5 =     0xd41d8cd98f00b204e9800998ecf8427e
+        if #available(
+            macOS 13.3,
+            macCatalyst 16.4,
+            iOS 16.4,
+            tvOS 16.4,
+            visionOS 1.0,
+            watchOS 9.4,
+            *)
+        {
+            let string:String = "d41d8cd98f00b204e9800998ecf8427e"
+            let hash:MD5 =     0xd41d8cd98f00b204e9800998ecf8427e
 
-        let parsed:MD5 = try #require(.init(string))
-        #expect(parsed == hash)
-        #expect(string == "\(hash)")
+            let parsed:MD5 = try #require(.init(string))
+            #expect(parsed == hash)
+            #expect(string == "\(hash)")
+        }
     }
 }