diff --git a/src/compiler/scanner.ts b/src/compiler/scanner.ts
index e404a6eb15c94..7d65a0c57551c 100644
--- a/src/compiler/scanner.ts
+++ b/src/compiler/scanner.ts
@@ -1640,7 +1640,7 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
                     const nextStart = pos;
                     let nextPos = pos + 2;
                     for (; nextPos < nextStart + 6; nextPos++) {
-                        if (!isHexDigit(charCodeUnchecked(pos))) {
+                        if (!isHexDigit(charCodeUnchecked(nextPos))) {
                             // leave the error to the next call
                             return escapedValueString;
                         }
@@ -3549,7 +3549,7 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
         }
 
         function scanSourceCharacter(): string {
-            const size = anyUnicodeMode ? charSize(charCodeChecked(pos)) : 1;
+            const size = anyUnicodeMode ? charSize(codePointChecked(pos)) : 1;
             pos += size;
             return size > 0 ? text.substring(pos - size, pos) : "";
         }
diff --git a/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.errors.txt b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.errors.txt
new file mode 100644
index 0000000000000..a3ece5fedce8b
--- /dev/null
+++ b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.errors.txt
@@ -0,0 +1,64 @@
+regularExpressionCharacterClassRangeOrder.ts(7,5): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(7,12): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(8,11): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(9,11): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(11,6): error TS1125: Hexadecimal digit expected.
+regularExpressionCharacterClassRangeOrder.ts(11,16): error TS1125: Hexadecimal digit expected.
+regularExpressionCharacterClassRangeOrder.ts(11,27): error TS1125: Hexadecimal digit expected.
+regularExpressionCharacterClassRangeOrder.ts(11,37): error TS1125: Hexadecimal digit expected.
+regularExpressionCharacterClassRangeOrder.ts(12,25): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(13,25): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(15,10): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(15,37): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(16,31): error TS1517: Range out of order in character class.
+regularExpressionCharacterClassRangeOrder.ts(17,31): error TS1517: Range out of order in character class.
+
+
+==== regularExpressionCharacterClassRangeOrder.ts (14 errors) ====
+    // The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+    // - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+    // - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+    //
+    // See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+    const regexes: RegExp[] = [
+    	/[𝘈-𝘡][𝘡-𝘈]/,
+    	   ~~~
+!!! error TS1517: Range out of order in character class.
+    	          ~~~
+!!! error TS1517: Range out of order in character class.
+    	/[𝘈-𝘡][𝘡-𝘈]/u,
+    	         ~~~~~
+!!! error TS1517: Range out of order in character class.
+    	/[𝘈-𝘡][𝘡-𝘈]/v,
+    	         ~~~~~
+!!! error TS1517: Range out of order in character class.
+    
+    	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+    	    
+!!! error TS1125: Hexadecimal digit expected.
+    	              
+!!! error TS1125: Hexadecimal digit expected.
+    	                         
+!!! error TS1125: Hexadecimal digit expected.
+    	                                   
+!!! error TS1125: Hexadecimal digit expected.
+    	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+    	                       ~~~~~~~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+    	                       ~~~~~~~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    
+    	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+    	        ~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    	                                   ~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+    	                             ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+    	                             ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1517: Range out of order in character class.
+    ];
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.js b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.js
new file mode 100644
index 0000000000000..9580f94588c19
--- /dev/null
+++ b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.js
@@ -0,0 +1,40 @@
+//// [tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts] ////
+
+//// [regularExpressionCharacterClassRangeOrder.ts]
+// The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+// - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+// - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+//
+// See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+const regexes: RegExp[] = [
+	/[𝘈-𝘡][𝘡-𝘈]/,
+	/[𝘈-𝘡][𝘡-𝘈]/u,
+	/[𝘈-𝘡][𝘡-𝘈]/v,
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+];
+
+
+//// [regularExpressionCharacterClassRangeOrder.js]
+// The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+// - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+// - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+//
+// See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+const regexes = [
+    /[𝘈-𝘡][𝘡-𝘈]/,
+    /[𝘈-𝘡][𝘡-𝘈]/u,
+    /[𝘈-𝘡][𝘡-𝘈]/v,
+    /[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+    /[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+    /[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+    /[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+    /[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+    /[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+];
diff --git a/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.symbols b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.symbols
new file mode 100644
index 0000000000000..f660554f89ddf
--- /dev/null
+++ b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.symbols
@@ -0,0 +1,25 @@
+//// [tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts] ////
+
+=== regularExpressionCharacterClassRangeOrder.ts ===
+// The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+// - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+// - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+//
+// See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+const regexes: RegExp[] = [
+>regexes : Symbol(regexes, Decl(regularExpressionCharacterClassRangeOrder.ts, 5, 5))
+>RegExp : Symbol(RegExp, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2018.regexp.d.ts, --, --) ... and 3 more)
+
+	/[𝘈-𝘡][𝘡-𝘈]/,
+	/[𝘈-𝘡][𝘡-𝘈]/u,
+	/[𝘈-𝘡][𝘡-𝘈]/v,
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+];
+
diff --git a/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.types b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.types
new file mode 100644
index 0000000000000..86f8d58e4d2bb
--- /dev/null
+++ b/tests/baselines/reference/regularExpressionCharacterClassRangeOrder.types
@@ -0,0 +1,52 @@
+//// [tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts] ////
+
+=== regularExpressionCharacterClassRangeOrder.ts ===
+// The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+// - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+// - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+//
+// See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+const regexes: RegExp[] = [
+>regexes : RegExp[]
+>        : ^^^^^^^^
+>[	/[𝘈-𝘡][𝘡-𝘈]/,	/[𝘈-𝘡][𝘡-𝘈]/u,	/[𝘈-𝘡][𝘡-𝘈]/v,	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,] : RegExp[]
+>                                                                                                                                                                                                                                                                                                                                                                                       : ^^^^^^^^
+
+	/[𝘈-𝘡][𝘡-𝘈]/,
+>/[𝘈-𝘡][𝘡-𝘈]/ : RegExp
+>                 : ^^^^^^
+
+	/[𝘈-𝘡][𝘡-𝘈]/u,
+>/[𝘈-𝘡][𝘡-𝘈]/u : RegExp
+>                  : ^^^^^^
+
+	/[𝘈-𝘡][𝘡-𝘈]/v,
+>/[𝘈-𝘡][𝘡-𝘈]/v : RegExp
+>                  : ^^^^^^
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+>/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/ : RegExp
+>                                             : ^^^^^^
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+>/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u : RegExp
+>                                              : ^^^^^^
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+>/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v : RegExp
+>                                              : ^^^^^^
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+>/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/ : RegExp
+>                                                         : ^^^^^^
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+>/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u : RegExp
+>                                                          : ^^^^^^
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+>/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v : RegExp
+>                                                          : ^^^^^^
+
+];
+
diff --git a/tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts b/tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts
new file mode 100644
index 0000000000000..a5d7799241594
--- /dev/null
+++ b/tests/cases/compiler/regularExpressionCharacterClassRangeOrder.ts
@@ -0,0 +1,20 @@
+// @target: esnext
+
+// The characters in the following regular expressions are ASCII-lookalike characters found in Unicode, including:
+// - 𝘈 (U+1D608 Mathematical Sans-Serif Italic Capital A)
+// - 𝘡 (U+1D621 Mathematical Sans-Serif Italic Capital Z)
+//
+// See https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols
+const regexes: RegExp[] = [
+	/[𝘈-𝘡][𝘡-𝘈]/,
+	/[𝘈-𝘡][𝘡-𝘈]/u,
+	/[𝘈-𝘡][𝘡-𝘈]/v,
+
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/u,
+	/[\u{1D608}-\u{1D621}][\u{1D621}-\u{1D608}]/v,
+
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/u,
+	/[\uD835\uDE08-\uD835\uDE21][\uD835\uDE21-\uD835\uDE08]/v,
+];