diff --git a/ts/input/tex/ParseMethods.ts b/ts/input/tex/ParseMethods.ts
index ec87d6b57..1055e371b 100644
--- a/ts/input/tex/ParseMethods.ts
+++ b/ts/input/tex/ParseMethods.ts
@@ -40,10 +40,11 @@ namespace ParseMethods {
   export function variable(parser: TexParser, c: string) {
     // @test Identifier Font
     const def = ParseUtil.getFontDef(parser);
-    if (parser.stack.env.multiLetterIdentifiers && parser.stack.env.font !== '') {
-      c = parser.string.substr(parser.i - 1).match(/^[a-z]+/i)[0];
+    const env = parser.stack.env;
+    if (env.multiLetterIdentifiers && env.font !== '') {
+      c = parser.string.substr(parser.i - 1).match(env.multiLetterIdentifiers as RegExp)[0];
       parser.i += c.length - 1;
-      if (def.mathvariant === TexConstant.Variant.NORMAL) {
+      if (def.mathvariant === TexConstant.Variant.NORMAL && env.noAutoOP && c.length > 1) {
         def.autoOP = false;
       }
     }
diff --git a/ts/input/tex/StackItem.ts b/ts/input/tex/StackItem.ts
index f6d01417c..2175f9d4b 100644
--- a/ts/input/tex/StackItem.ts
+++ b/ts/input/tex/StackItem.ts
@@ -28,7 +28,7 @@ import TexError from './TexError.js';
 import StackItemFactory from './StackItemFactory.js';
 
 // Union types for abbreviation.
-export type EnvProp = string | number | boolean;
+export type EnvProp = string | number | boolean | RegExp;
 
 export type EnvList = {[key: string]: EnvProp};
 
diff --git a/ts/input/tex/ams/AmsConfiguration.ts b/ts/input/tex/ams/AmsConfiguration.ts
index 0fd4f7ce2..31d2c3d41 100644
--- a/ts/input/tex/ams/AmsConfiguration.ts
+++ b/ts/input/tex/ams/AmsConfiguration.ts
@@ -51,6 +51,7 @@ let init = function(config: ParserConfiguration) {
 export const AmsConfiguration = Configuration.create(
   'ams', {
     handler: {
+      character: ['AMSmath-operatorLetter'],
       delimiter: ['AMSsymbols-delimiter', 'AMSmath-delimiter'],
       macro: ['AMSsymbols-mathchar0mi', 'AMSsymbols-mathchar0mo',
               'AMSsymbols-delimiter', 'AMSsymbols-macros',
diff --git a/ts/input/tex/ams/AmsMappings.ts b/ts/input/tex/ams/AmsMappings.ts
index 974929baf..b2e0f15c2 100644
--- a/ts/input/tex/ams/AmsMappings.ts
+++ b/ts/input/tex/ams/AmsMappings.ts
@@ -39,6 +39,10 @@ new sm.CharacterMap('AMSmath-mathchar0mo', ParseMethods.mathchar0mo, {
   iiiint:     ['\u2A0C', {texClass: TEXCLASS.OP}]
 });
 
+/**
+ * Extra characters that are letters in \operatorname
+ */
+new sm.RegExpMap('AMSmath-operatorLetter', AmsMethods.operatorLetter, /[-*]/i);
 
 /**
  * Macros from the AMS Math package.
diff --git a/ts/input/tex/ams/AmsMethods.ts b/ts/input/tex/ams/AmsMethods.ts
index dfaa98e79..fd5c5e8c1 100644
--- a/ts/input/tex/ams/AmsMethods.ts
+++ b/ts/input/tex/ams/AmsMethods.ts
@@ -26,6 +26,7 @@
 import {StackItem} from '../StackItem.js';
 import {ParseMethod} from '../Types.js';
 import ParseUtil from '../ParseUtil.js';
+import ParseMethods from '../ParseMethods.js';
 import NodeUtil from '../NodeUtil.js';
 import {TexConstant} from '../TexConstants.js';
 import TexParser from '../TexParser.js';
@@ -202,17 +203,14 @@ export const NEW_OPS = 'ams-declare-ops';
  * @param {string} name The macro name.
  */
 AmsMethods.HandleDeclareOp =  function (parser: TexParser, name: string) {
-  let limits = (parser.GetStar() ? '' : '\\nolimits\\SkipLimits');
+  let star = (parser.GetStar() ? '*' : '');
   let cs = ParseUtil.trimSpaces(parser.GetArgument(name));
   if (cs.charAt(0) === '\\') {
     cs = cs.substr(1);
   }
   let op = parser.GetArgument(name);
-  if (!op.match(/\\text/)) {
-    op = op.replace(/\*/g, '\\text{*}').replace(/-/g, '\\text{-}');
-  }
   (parser.configuration.handlers.retrieve(NEW_OPS) as CommandMap).
-    add(cs, new Macro(cs, AmsMethods.Macro, ['\\mathop{\\rm ' + op + '}' + limits]));
+    add(cs, new Macro(cs, AmsMethods.Macro, [`\\operatorname${star}{${op}}`]));
 };
 
 
@@ -223,28 +221,47 @@ AmsMethods.HandleDeclareOp =  function (parser: TexParser, name: string) {
  */
 AmsMethods.HandleOperatorName = function(parser: TexParser, name: string) {
   // @test Operatorname
-  const limits = (parser.GetStar() ? '' : '\\nolimits\\SkipLimits');
+  const star = parser.GetStar();
+  //
+  //  Parse the argument using operator letters and grouping multiple letters.
+  //
   let op = ParseUtil.trimSpaces(parser.GetArgument(name));
-  if (!op.match(/\\text/)) {
-    op = op.replace(/\*/g, '\\text{*}').replace(/-/g, '\\text{-}');
+  let mml = new TexParser(op, {
+    ...parser.stack.env,
+    font: TexConstant.Variant.NORMAL,
+    multiLetterIdentifiers: /^[-*a-z]+/i,
+    operatorLetters: true
+  }, parser.configuration).mml();
+  //
+  //  If we get something other than a single mi, wrap in a TeXAtom.
+  //
+  if (!mml.isKind('mi')) {
+    mml = parser.create('node', 'TeXAtom', [mml]);
   }
-  parser.string = '\\mathop{\\rm ' + op + '}' + limits + ' ' +
-    parser.string.slice(parser.i);
-  parser.i = 0;
+  //
+  //  Mark the limit properties and the TeX class.
+  //
+  NodeUtil.setProperties(mml, {movesupsub: star, movablelimits: true, texClass: TEXCLASS.OP});
+  //
+  //  Skip a following \limits macro if not a starred operator
+  //
+  if (!star) {
+    const c = parser.GetNext(), i = parser.i;
+    if (c === '\\' && ++parser.i && parser.GetCS() !== 'limits') {
+      parser.i = i;
+    }
+  }
+  //
+  parser.Push(mml);
 };
 
-
 /**
- * Handle SkipLimits.
+ * Handle extra letters in \operatorname (- and *), default to normal otherwise.
  * @param {TexParser} parser The calling parser.
- * @param {string} name The macro name.
+ * @param {string} c The letter being checked
  */
-AmsMethods.SkipLimits = function(parser: TexParser, _name: string) {
-  // @test Operatorname
-  const c = parser.GetNext(), i = parser.i;
-  if (c === '\\' && ++parser.i && parser.GetCS() !== 'limits') {
-    parser.i = i;
-  }
+AmsMethods.operatorLetter = function (parser: TexParser, c: string) {
+  return parser.stack.env.operatorLetters ? ParseMethods.variable(parser, c) : false;
 };
 
 
diff --git a/ts/input/tex/base/BaseMethods.ts b/ts/input/tex/base/BaseMethods.ts
index 77d2e0bc3..62f72a8ec 100644
--- a/ts/input/tex/base/BaseMethods.ts
+++ b/ts/input/tex/base/BaseMethods.ts
@@ -282,7 +282,8 @@ BaseMethods.MathFont = function(parser: TexParser, name: string, variant: string
   let mml = new TexParser(text, {
     ...parser.stack.env,
     font: variant,
-    multiLetterIdentifiers: true
+    multiLetterIdentifiers: /^[a-z]+/i,
+    noAutoOP: true
   }, parser.configuration).mml();
   parser.Push(parser.create('node', 'TeXAtom', [mml]));
 };