diff --git a/Package.swift b/Package.swift
index 5d45950db..f02ef1828 100644
--- a/Package.swift
+++ b/Package.swift
@@ -7,7 +7,7 @@ let availabilityDefinition = PackageDescription.SwiftSetting.unsafeFlags([
     "-Xfrontend",
     "-define-availability",
     "-Xfrontend",
-    "SwiftStdlib 5.7:macOS 9999, iOS 9999, watchOS 9999, tvOS 9999",
+    "SwiftStdlib 5.7:macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0",
     "-Xfrontend",
     "-define-availability",
     "-Xfrontend",
diff --git a/Sources/RegexBenchmark/BenchmarkRunner.swift b/Sources/RegexBenchmark/BenchmarkRunner.swift
index 1a62858c1..641c03224 100644
--- a/Sources/RegexBenchmark/BenchmarkRunner.swift
+++ b/Sources/RegexBenchmark/BenchmarkRunner.swift
@@ -1,6 +1,9 @@
 import Foundation
 @_spi(RegexBenchmark) import _StringProcessing
 
+/// The number of times to re-run the benchmark if results are too varying
+private var rerunCount: Int { 3 }
+
 struct BenchmarkRunner {
   let suiteName: String
   var suite: [any RegexBenchmark] = []
@@ -82,11 +85,16 @@ struct BenchmarkRunner {
     for b in suite {
       var result = measure(benchmark: b, samples: samples)
       if result.runtimeIsTooVariant {
-        print("Warning: Standard deviation > \(Stats.maxAllowedStdev*100)% for \(b.name)")
-        print(result.runtime)
-        print("Rerunning \(b.name)")
-        result = measure(benchmark: b, samples: result.runtime.samples*2)
-        print(result.runtime)
+        for _ in 0..<rerunCount {
+          print("Warning: Standard deviation > \(Stats.maxAllowedStdev*100)% for \(b.name)")
+          print(result.runtime)
+          print("Rerunning \(b.name)")
+          result = measure(benchmark: b, samples: result.runtime.samples*2)
+          print(result.runtime)
+          if !result.runtimeIsTooVariant {
+            break
+          }
+        }
         if result.runtimeIsTooVariant {
           fatalError("Benchmark \(b.name) is too variant")
         }
diff --git a/Sources/_StringProcessing/Engine/MEBuiltins.swift b/Sources/_StringProcessing/Engine/MEBuiltins.swift
index 36a6043fe..6f99058fd 100644
--- a/Sources/_StringProcessing/Engine/MEBuiltins.swift
+++ b/Sources/_StringProcessing/Engine/MEBuiltins.swift
@@ -38,9 +38,9 @@ extension Processor {
       return nil
     }
 
-    let asciiCheck = (char.isASCII && !isScalarSemantics)
+    let asciiCheck = !isStrictASCII
       || (scalar.isASCII && isScalarSemantics)
-      || !isStrictASCII
+      || char.isASCII
 
     var matched: Bool
     var next: Input.Index
diff --git a/Sources/_StringProcessing/_CharacterClassModel.swift b/Sources/_StringProcessing/_CharacterClassModel.swift
index c5f1f8ecd..548a9eea0 100644
--- a/Sources/_StringProcessing/_CharacterClassModel.swift
+++ b/Sources/_StringProcessing/_CharacterClassModel.swift
@@ -81,9 +81,10 @@ struct _CharacterClassModel: Hashable {
     let char = input[currentPosition]
     let scalar = input.unicodeScalars[currentPosition]
     let isScalarSemantics = matchLevel == .unicodeScalar
-    let asciiCheck = (char.isASCII && !isScalarSemantics)
+
+    let asciiCheck = !isStrictASCII
       || (scalar.isASCII && isScalarSemantics)
-      || !isStrictASCII
+      || char.isASCII
     
     var matched: Bool
     var next: String.Index