diff --git a/benchmark/Package.swift b/benchmark/Package.swift
index cb6c0ecdf4f14..4e31fdd2ef3fb 100644
--- a/benchmark/Package.swift
+++ b/benchmark/Package.swift
@@ -22,19 +22,19 @@ func getSingleSourceLibraries(subDirectory: String) -> [String] {
   let fileURLs = try! f.contentsOfDirectory(at: dirURL,
                                             includingPropertiesForKeys: nil)
   return fileURLs.compactMap { (path: URL) -> String? in
-    let c = path.lastPathComponent.split(separator: ".")
-    // Too many components. Must be a gyb file.
-    if c.count > 2 {
-      return nil
-    }
-    if c[1] != "swift" {
+    guard let lastDot = path.lastPathComponent.lastIndex(of: ".") else {
       return nil
     }
+    let ext = String(path.lastPathComponent.suffix(from: lastDot))
+    guard ext == ".swift" else { return nil }
+
+    let name = String(path.lastPathComponent.prefix(upTo: lastDot))
 
-    let name = String(c[0])
+    // Test names must have a single component.
+    if name.contains(".") { return nil }
 
-    // We do not support this test.
     if unsupportedTests.contains(name) {
+      // We do not support this test.
       return nil
     }