diff --git a/Tests/RegexBuilderTests/GoodBadFunctionTests.swift b/Tests/RegexBuilderTests/GoodBadFunctionTests.swift
new file mode 100644
index 000000000..33af425fb
--- /dev/null
+++ b/Tests/RegexBuilderTests/GoodBadFunctionTests.swift
@@ -0,0 +1,18 @@
+import XCTest
+import _StringProcessing
+@testable import RegexBuilder
+
+func goodFunction<T>(_ r: some RegexComponent<T>) {
+  _ = try? r.regex.firstMatch(in: "...")
+}
+
+fileprivate func badFunction<T>(_ r: Regex<T>) {
+  _ = try? r.firstMatch(in: "...")
+}
+
+class GoodBadFunctionTests: XCTestCase {
+  func testGoodBadFunctions() {
+    goodFunction(Regex { "asdf" })
+    badFunction(Regex { "asdf" })
+  }
+}