diff --git a/Sources/BuildServerProtocol/Messages/InitializeBuildRequest.swift b/Sources/BuildServerProtocol/Messages/InitializeBuildRequest.swift
index bbf2deb3..9e20afdd 100644
--- a/Sources/BuildServerProtocol/Messages/InitializeBuildRequest.swift
+++ b/Sources/BuildServerProtocol/Messages/InitializeBuildRequest.swift
@@ -283,11 +283,11 @@ public struct SourceKitInitializeBuildResponseData: LSPAnyCodable, Codable, Send
   public var sourceKitOptionsProvider: Bool?
 
   public init(
-    indexDatabasePath: String?,
-    indexStorePath: String?,
-    watchers: [FileSystemWatcher]?,
-    prepareProvider: Bool?,
-    sourceKitOptionsProvider: Bool?
+    indexDatabasePath: String? = nil,
+    indexStorePath: String? = nil,
+    watchers: [FileSystemWatcher]? = nil,
+    prepareProvider: Bool? = nil,
+    sourceKitOptionsProvider: Bool? = nil
   ) {
     self.indexDatabasePath = indexDatabasePath
     self.indexStorePath = indexStorePath
diff --git a/Sources/BuildSystemIntegration/TestBuildSystem.swift b/Sources/BuildSystemIntegration/TestBuildSystem.swift
index 018f5cac..9d726cb2 100644
--- a/Sources/BuildSystemIntegration/TestBuildSystem.swift
+++ b/Sources/BuildSystemIntegration/TestBuildSystem.swift
@@ -37,9 +37,15 @@ package actor TestBuildSystem: MessageHandler {
     connectionToSourceKitLSP.send(OnBuildTargetDidChangeNotification(changes: nil))
   }
 
-  package nonisolated var supportsPreparation: Bool { false }
+  private let initializeData: SourceKitInitializeBuildResponseData
 
-  package init(connectionToSourceKitLSP: any Connection) {
+  package init(
+    initializeData: SourceKitInitializeBuildResponseData = SourceKitInitializeBuildResponseData(
+      sourceKitOptionsProvider: true
+    ),
+    connectionToSourceKitLSP: any Connection
+  ) {
+    self.initializeData = initializeData
     self.connectionToSourceKitLSP = connectionToSourceKitLSP
   }
 
@@ -90,6 +96,8 @@ package actor TestBuildSystem: MessageHandler {
       handle(request, using: self.workspaceBuildTargetsRequest)
     case let request as WorkspaceWaitForBuildSystemUpdatesRequest:
       handle(request, using: self.workspaceWaitForBuildSystemUpdatesRequest)
+    case let request as BuildTargetPrepareRequest:
+      handle(request, using: self.prepareTarget)
     default:
       reply(.failure(ResponseError.methodNotFound(type(of: request).method)))
     }
@@ -101,7 +109,8 @@ package actor TestBuildSystem: MessageHandler {
       version: "",
       bspVersion: "2.2.0",
       capabilities: BuildServerCapabilities(),
-      data: nil
+      dataKind: .sourceKit,
+      data: initializeData.encodeToLSPAny()
     )
   }
 
@@ -148,6 +157,10 @@ package actor TestBuildSystem: MessageHandler {
     return buildSettingsByFile[request.textDocument.uri]
   }
 
+  func prepareTarget(_ request: BuildTargetPrepareRequest) async throws -> VoidResponse {
+    return VoidResponse()
+  }
+
   package func waitForBuildSystemUpdates(request: WorkspaceWaitForBuildSystemUpdatesRequest) async -> VoidResponse {
     return VoidResponse()
   }
diff --git a/Sources/SemanticIndex/SemanticIndexManager.swift b/Sources/SemanticIndex/SemanticIndexManager.swift
index 9550c329..bb8ff355 100644
--- a/Sources/SemanticIndex/SemanticIndexManager.swift
+++ b/Sources/SemanticIndex/SemanticIndexManager.swift
@@ -673,7 +673,7 @@ package final actor SemanticIndexManager {
   /// `indexFilesWithUpToDateUnit` is `true`.
   ///
   /// The returned task finishes when all files are indexed.
-  private func scheduleIndexing(
+  package func scheduleIndexing(
     of files: some Collection<DocumentURI> & Sendable,
     indexFilesWithUpToDateUnit: Bool,
     priority: TaskPriority?
diff --git a/Sources/SourceKitLSP/Workspace.swift b/Sources/SourceKitLSP/Workspace.swift
index 74fc6374..58d4ccbd 100644
--- a/Sources/SourceKitLSP/Workspace.swift
+++ b/Sources/SourceKitLSP/Workspace.swift
@@ -435,8 +435,24 @@ package final class Workspace: Sendable, BuildSystemManagerDelegate {
 
   package func buildTargetsChanged(_ changes: [BuildTargetEvent]?) async {
     await sourceKitLSPServer?.fileHandlingCapabilityChanged()
-    let testFiles = await orLog("Getting test files") { try await buildSystemManager.testFiles() } ?? []
-    await syntacticTestIndex.listOfTestFilesDidChange(testFiles)
+    await orLog("Scheduling re-indexing of changed targets") {
+      var sourceFiles = try await self.buildSystemManager.sourceFiles(includeNonBuildableFiles: false)
+      if let changes {
+        let changedTargets = changes.map(\.target)
+        sourceFiles = sourceFiles.filter {
+          !$0.value.targets.intersection(changedTargets).isEmpty
+        }
+      }
+      _ = await semanticIndexManager?.scheduleIndexing(
+        of: sourceFiles.keys,
+        indexFilesWithUpToDateUnit: false,
+        priority: .low
+      )
+    }
+    await orLog("Scheduling syntactic test re-indexing") {
+      let testFiles = try await buildSystemManager.testFiles()
+      await syntacticTestIndex.listOfTestFilesDidChange(testFiles)
+    }
   }
 
   package var clientSupportsWorkDoneProgress: Bool {
diff --git a/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift b/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
index 6dee3b09..abcf4e67 100644
--- a/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
+++ b/Tests/SourceKitLSPTests/BackgroundIndexingTests.swift
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import BuildServerProtocol
 import BuildSystemIntegration
 import LanguageServerProtocol
 import LanguageServerProtocolExtensions
@@ -1910,6 +1911,72 @@ final class BackgroundIndexingTests: XCTestCase {
       try await project.testClient.send(IsIndexingRequest()).indexing == false
     }
   }
+
+  func testIndexFileIfBuildTargetsChange() async throws {
+    let testBuildSystem = ThreadSafeBox<TestBuildSystem?>(initialValue: nil)
+    let project = try await MultiFileTestProject(
+      files: [
+        "Test.swift": """
+        func 1️⃣myTestFunc() {}
+        """
+      ],
+      hooks: Hooks(
+        buildSystemHooks: BuildSystemHooks(injectBuildServer: { projectRoot, connectionToSourceKitLSP in
+          assert(testBuildSystem.value == nil, "Build system injector hook can only create a single TestBuildSystem")
+          let buildSystem = TestBuildSystem(
+            initializeData: SourceKitInitializeBuildResponseData(
+              indexDatabasePath: projectRoot.appendingPathComponent("index-db").path,
+              indexStorePath: projectRoot.appendingPathComponent("index-store").path,
+              prepareProvider: true,
+              sourceKitOptionsProvider: true
+            ),
+            connectionToSourceKitLSP: connectionToSourceKitLSP
+          )
+          testBuildSystem.value = buildSystem
+          let connection = LocalConnection(receiverName: "TestBuildSystem")
+          connection.start(handler: buildSystem)
+          return connection
+        })
+      ),
+      enableBackgroundIndexing: true
+    )
+    let fileUrl = try XCTUnwrap(project.uri(for: "Test.swift").fileURL)
+
+    var compilerArguments = [fileUrl.path]
+    if let defaultSDKPath {
+      compilerArguments += ["-sdk", defaultSDKPath]
+    }
+
+    // We don't initially index Test.swift because we don't have build settings for it.
+
+    try await XCTUnwrap(testBuildSystem.value).setBuildSettings(
+      for: DocumentURI(fileUrl),
+      to: TextDocumentSourceKitOptionsResponse(compilerArguments: compilerArguments)
+    )
+
+    // But once we get build settings for it, we should index the file.
+
+    try await repeatUntilExpectedResult {
+      let workspaceSymbols = try await project.testClient.send(WorkspaceSymbolsRequest(query: "myTestFunc"))
+      guard let workspaceSymbols, !workspaceSymbols.isEmpty else {
+        // No results yet, indexing of the file might not have finished.
+        return false
+      }
+      XCTAssertEqual(
+        workspaceSymbols,
+        [
+          .symbolInformation(
+            SymbolInformation(
+              name: "myTestFunc()",
+              kind: .function,
+              location: try project.location(from: "1️⃣", to: "1️⃣", in: "Test.swift")
+            )
+          )
+        ]
+      )
+      return true
+    }
+  }
 }
 
 extension HoverResponseContents {
diff --git a/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift b/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
index 4a9882a0..af743377 100644
--- a/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
+++ b/Tests/SourceKitLSPTests/WorkspaceSymbolsTests.swift
@@ -76,20 +76,14 @@ class WorkspaceSymbolsTests: XCTestCase {
           SymbolInformation(
             name: "afuncFromA()",
             kind: .function,
-            location: Location(
-              uri: try project.uri(for: "PackageALib.swift"),
-              range: Range(try project.position(of: "1️⃣", in: "PackageALib.swift"))
-            )
+            location: try project.location(from: "1️⃣", to: "1️⃣", in: "PackageALib.swift")
           )
         ),
         .symbolInformation(
           SymbolInformation(
             name: "funcFromB()",
             kind: .function,
-            location: Location(
-              uri: try project.uri(for: "PackageBLib.swift"),
-              range: Range(try project.position(of: "2️⃣", in: "PackageBLib.swift"))
-            )
+            location: try project.location(from: "2️⃣", to: "2️⃣", in: "PackageBLib.swift")
           )
         ),
       ]