diff --git a/.github/workflows/compatibility_tests.yml b/.github/workflows/compatibility_tests.yml
index 0e127baf..eb20b1ce 100644
--- a/.github/workflows/compatibility_tests.yml
+++ b/.github/workflows/compatibility_tests.yml
@@ -36,6 +36,8 @@ jobs:
       - name: Swift version
         run: swift --version
       - name: Run tests against Apple's AttributeGraph on macOS via SwiftPM
+        env:
+          OPENGRAPH_LIBRARY_EVOLUTION: 0
         run: |
           swift test \
             --build-path .build-compatibility-test-debug
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index f299b1c8..18fdca4e 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -35,6 +35,8 @@ jobs:
       - name: Swift version
         run: swift --version
       - name: Build and run tests in debug mode with coverage
+        env:
+          OPENGRAPH_LIBRARY_EVOLUTION: 0
         run: |
           swift test \
             -c debug \
@@ -45,6 +47,8 @@ jobs:
             .build-test-debug/debug/OpenGraphPackageTests.xctest/Contents/MacOS/OpenGraphPackageTests \
             > coverage.txt
       - name: Build and run tests in release mode
+        env:
+          OPENGRAPH_LIBRARY_EVOLUTION: 0
         run: |
           swift test \
             -c release \
diff --git a/Package.swift b/Package.swift
index 6b915acd..3394cf49 100644
--- a/Package.swift
+++ b/Package.swift
@@ -34,8 +34,8 @@ var sharedCSettings: [CSetting] = [
 
 var sharedSwiftSettings: [SwiftSetting] = [
     .enableUpcomingFeature("InternalImportsByDefault"),
+    .enableExperimentalFeature("Extern"),
     .swiftLanguageMode(.v5),
-    .unsafeFlags(["-enable-library-evolution"]),
 ]
 
 // MARK: [env] OPENGRAPH_SWIFT_TOOLCHAIN_PATH
@@ -119,6 +119,7 @@ let libraryEvolutionCondition = envEnable("OPENGRAPH_LIBRARY_EVOLUTION")
 #endif
 
 if libraryEvolutionCondition {
+    // NOTE:  -enable-library-evolution is not supported on `swift build` yet.
     sharedSwiftSettings.append(.unsafeFlags(["-enable-library-evolution"]))
 }
 
diff --git a/Sources/OpenGraph/Runtime/TupleType.swift b/Sources/OpenGraph/Runtime/TupleType.swift
index e8f296ff..fddf1e4b 100644
--- a/Sources/OpenGraph/Runtime/TupleType.swift
+++ b/Sources/OpenGraph/Runtime/TupleType.swift
@@ -75,15 +75,15 @@ extension UnsafeTuple {
 
 // MARK: - UnsafeMutableTuple
 
-@_silgen_name("swift_slowAlloc")
-private func slowAlloc(_ size: Int, _ alignMask: Int) -> UnsafeMutableRawPointer
-
-@_silgen_name("swift_slowDealloc")
-private func slowDealloc(_ ptr: UnsafeMutableRawPointer, _ size: Int, _ alignMask: Int)
-
 extension UnsafeMutableTuple {
     public init(with tupleType: TupleType) {
-        self.init(type: tupleType, value: slowAlloc(tupleType.size, -1))
+        self.init(
+            type: tupleType,
+            value: UnsafeMutableRawPointer.allocate(
+                byteCount: tupleType.size,
+                alignment: -1
+            )
+        )
     }
     
     public func initialize<T>(at index: Int, to element: T) {
@@ -104,7 +104,7 @@ extension UnsafeMutableTuple {
         if initialized {
             deinitialize()
         }
-        slowDealloc(value, -1, -1)
+        value.deallocate()
     }
     
     public var count: Int { type.count }