diff --git a/Sources/_StringProcessing/ByteCodeGen.swift b/Sources/_StringProcessing/ByteCodeGen.swift
index 15e052901..d4c91bd63 100644
--- a/Sources/_StringProcessing/ByteCodeGen.swift
+++ b/Sources/_StringProcessing/ByteCodeGen.swift
@@ -702,9 +702,6 @@ fileprivate extension Compiler.ByteCodeGen {
       case .characterClass(let cc):
         // Custom character class that consumes a single grapheme
         let model = cc.asRuntimeModel(options)
-        guard model.consumesSingleGrapheme else {
-          return false
-        }
         builder.buildQuantify(
           model: model,
           kind,
diff --git a/Sources/_StringProcessing/Engine/MEBuiltins.swift b/Sources/_StringProcessing/Engine/MEBuiltins.swift
index fa4f8fa1a..a3d864165 100644
--- a/Sources/_StringProcessing/Engine/MEBuiltins.swift
+++ b/Sources/_StringProcessing/Engine/MEBuiltins.swift
@@ -193,8 +193,6 @@ extension String {
     switch (isScalarSemantics, cc) {
     case (_, .anyGrapheme):
       next = index(after: currentPosition)
-    case (_, .anyScalar):
-      next = unicodeScalars.index(after: currentPosition)
     case (true, _):
       next = unicodeScalars.index(after: currentPosition)
     case (false, _):
@@ -204,12 +202,6 @@ extension String {
     switch cc {
     case .any, .anyGrapheme:
       matched = true
-    case .anyScalar:
-      if isScalarSemantics {
-        matched = true
-      } else {
-        matched = isOnGraphemeClusterBoundary(next)
-      }
     case .digit:
       if isScalarSemantics {
         matched = scalar.properties.numericType != nil && asciiCheck
diff --git a/Sources/_StringProcessing/PrintAsPattern.swift b/Sources/_StringProcessing/PrintAsPattern.swift
index 3d2d38842..08c40157a 100644
--- a/Sources/_StringProcessing/PrintAsPattern.swift
+++ b/Sources/_StringProcessing/PrintAsPattern.swift
@@ -760,8 +760,6 @@ extension DSLTree.Atom.CharacterClass {
     switch self {
     case .anyGrapheme:
       return ".anyGraphemeCluster"
-    case .anyUnicodeScalar:
-      return ".anyUnicodeScalar"
     case .digit:
       return ".digit"
     case .notDigit:
@@ -786,6 +784,8 @@ extension DSLTree.Atom.CharacterClass {
       return ".whitespace"
     case .notWhitespace:
       return ".whitespace.inverted"
+    case .anyUnicodeScalar:
+      fatalError("Unsupported")
     }
   }
 }
diff --git a/Sources/_StringProcessing/Regex/ASTConversion.swift b/Sources/_StringProcessing/Regex/ASTConversion.swift
index f5b08dd6d..6af0924cb 100644
--- a/Sources/_StringProcessing/Regex/ASTConversion.swift
+++ b/Sources/_StringProcessing/Regex/ASTConversion.swift
@@ -183,7 +183,6 @@ extension AST.Atom.EscapedBuiltin {
     case .wordCharacter:            return .word
     case .notWordCharacter:         return .notWord
     case .graphemeCluster:          return .anyGrapheme
-    case .trueAnychar:              return .anyUnicodeScalar
     default: return nil
     }
   }
diff --git a/Sources/_StringProcessing/Regex/DSLTree.swift b/Sources/_StringProcessing/Regex/DSLTree.swift
index 93e86c607..b784e2382 100644
--- a/Sources/_StringProcessing/Regex/DSLTree.swift
+++ b/Sources/_StringProcessing/Regex/DSLTree.swift
@@ -260,7 +260,6 @@ extension DSLTree.Atom.CharacterClass {
   public var inverted: DSLTree.Atom.CharacterClass? {
     switch self {
     case .anyGrapheme: return nil
-    case .anyUnicodeScalar: return nil
     case .digit: return .notDigit
     case .notDigit: return .digit
     case .word: return .notWord
@@ -273,6 +272,8 @@ extension DSLTree.Atom.CharacterClass {
     case .notVerticalWhitespace: return .verticalWhitespace
     case .whitespace: return .notWhitespace
     case .notWhitespace: return .whitespace
+    case .anyUnicodeScalar:
+      fatalError("Unsupported")
     }
   }
 }
diff --git a/Sources/_StringProcessing/Unicode/ASCII.swift b/Sources/_StringProcessing/Unicode/ASCII.swift
index f27584893..5150e18cc 100644
--- a/Sources/_StringProcessing/Unicode/ASCII.swift
+++ b/Sources/_StringProcessing/Unicode/ASCII.swift
@@ -134,8 +134,7 @@ extension String {
 
     // TODO: bitvectors
     switch cc {
-    case .any, .anyGrapheme, .anyScalar:
-      // TODO: should any scalar not consume CR-LF in scalar semantic mode?
+    case .any, .anyGrapheme:
       return (next, true)
 
     case .digit:
diff --git a/Sources/_StringProcessing/_CharacterClassModel.swift b/Sources/_StringProcessing/_CharacterClassModel.swift
index 35a11a7ef..cdee66ddb 100644
--- a/Sources/_StringProcessing/_CharacterClassModel.swift
+++ b/Sources/_StringProcessing/_CharacterClassModel.swift
@@ -45,8 +45,6 @@ struct _CharacterClassModel: Hashable {
     case any = 0
     /// Any grapheme cluster
     case anyGrapheme
-    /// Any Unicode scalar
-    case anyScalar
     /// Character.isDigit
     case digit
     /// Horizontal whitespace: `[:blank:]`, i.e
@@ -90,15 +88,6 @@ struct _CharacterClassModel: Hashable {
   }
 }
 
-extension _CharacterClassModel {
-  var consumesSingleGrapheme: Bool {
-   switch self.cc {
-    case .anyScalar: return false
-    default: return true
-    }
-  }
-}
-
 extension _CharacterClassModel.Representation {
   /// Returns true if this CharacterClass should be matched by strict ascii under the given options
   func isStrictAscii(options: MatchingOptions) -> Bool {
@@ -119,7 +108,6 @@ extension _CharacterClassModel.Representation: CustomStringConvertible {
     switch self {
     case .any: return "<any>"
     case .anyGrapheme: return "<any grapheme>"
-    case .anyScalar: return "<any scalar>"
     case .digit: return "<digit>"
     case .horizontalWhitespace: return "<horizontal whitespace>"
     case .newlineSequence: return "<newline sequence>"
@@ -185,7 +173,7 @@ extension DSLTree.Atom.CharacterClass {
     case .anyGrapheme:
       cc = .anyGrapheme
     case .anyUnicodeScalar:
-      cc = .anyScalar
+      fatalError("Unsupported")
     }
     return _CharacterClassModel(cc: cc, options: options, isInverted: inverted)
   }