diff --git a/Sources/Workspace/Destination.swift b/Sources/Workspace/Destination.swift
index e681496b96f..78fd171dc1c 100644
--- a/Sources/Workspace/Destination.swift
+++ b/Sources/Workspace/Destination.swift
@@ -37,7 +37,7 @@ public struct Destination: Encodable {
     public let target: Triple
 
     /// The SDK used to compile for the destination.
-    public let sdk: AbsolutePath
+    public let sdk: AbsolutePath?
 
     /// The binDir in the containing the compilers/linker to be used for the compilation.
     public let binDir: AbsolutePath
@@ -112,7 +112,7 @@ public struct Destination: Encodable {
       #else
         return Destination(
             target: hostTargetTriple,
-            sdk: .root,
+            sdk: nil,
             binDir: binDir,
             extraCCFlags: ["-fPIC"],
             extraSwiftCFlags: [],
diff --git a/Sources/Workspace/UserToolchain.swift b/Sources/Workspace/UserToolchain.swift
index 97a46cc649f..dfb4b23642d 100644
--- a/Sources/Workspace/UserToolchain.swift
+++ b/Sources/Workspace/UserToolchain.swift
@@ -221,14 +221,19 @@ public final class UserToolchain: Toolchain {
         self.xctest = nil
       #endif
 
-        self.extraSwiftCFlags = (destination.target.isDarwin()
-                                    ? ["-sdk", destination.sdk.pathString]
+        if let sdk = destination.sdk {
+            self.extraSwiftCFlags = (destination.target.isDarwin()
+                                    ? ["-sdk", sdk.pathString]
                                     : [])
                                   + destination.extraSwiftCFlags
 
-        self.extraCCFlags = [
-            destination.target.isDarwin() ? "-isysroot" : "--sysroot", destination.sdk.pathString
-        ] + destination.extraCCFlags
+            self.extraCCFlags = [
+                destination.target.isDarwin() ? "-isysroot" : "--sysroot", sdk.pathString
+            ] + destination.extraCCFlags
+        } else {
+            self.extraSwiftCFlags = destination.extraSwiftCFlags
+            self.extraCCFlags = destination.extraCCFlags
+        }
 
         // Compute the path of directory containing the PackageDescription libraries.
         var pdLibDir = UserManifestResources.libDir(forBinDir: binDir)