diff --git a/demo/markdownlint-browser.js b/demo/markdownlint-browser.js
index 9ecccfc9..782ce28e 100644
--- a/demo/markdownlint-browser.js
+++ b/demo/markdownlint-browser.js
@@ -4521,9 +4521,8 @@ module.exports = {
 
 
 
-const { addErrorContext, filterTokens } = __webpack_require__(/*! ../helpers */ "../helpers/helpers.js");
-
-const spaceBeforeHeadingRe = /^(\s+|[>\s]+\s\s)[^>\s]/;
+const { addErrorContext } = __webpack_require__(/*! ../helpers */ "../helpers/helpers.js");
+const { filterByTypes } = __webpack_require__(/*! ../helpers/micromark.cjs */ "../helpers/micromark.cjs");
 
 // eslint-disable-next-line jsdoc/valid-types
 /** @type import("./markdownlint").Rule */
@@ -4531,31 +4530,34 @@ module.exports = {
   "names": [ "MD023", "heading-start-left" ],
   "description": "Headings must start at the beginning of the line",
   "tags": [ "headings", "spaces" ],
-  "parser": "markdownit",
+  "parser": "micromark",
   "function": function MD023(params, onError) {
-    filterTokens(params, "heading_open", function forToken(token) {
-      const { lineNumber, line } = token;
-      const match = line.match(spaceBeforeHeadingRe);
-      if (match) {
-        const [ prefixAndFirstChar, prefix ] = match;
-        let deleteCount = prefix.length;
-        const prefixLengthNoSpace = prefix.trimEnd().length;
-        if (prefixLengthNoSpace) {
-          deleteCount -= prefixLengthNoSpace - 1;
-        }
+    const headings = filterByTypes(
+      params.parsers.micromark.tokens,
+      [ "atxHeading", "linePrefix", "setextHeading" ]
+    );
+    for (let i = 0; i < headings.length - 1; i++) {
+      if (
+        (headings[i].type === "linePrefix") &&
+        (headings[i + 1].type !== "linePrefix") &&
+        (headings[i].startLine === headings[i + 1].startLine)
+      ) {
+        const { endColumn, startColumn, startLine } = headings[i];
+        const length = endColumn - startColumn;
         addErrorContext(
           onError,
-          lineNumber,
-          line,
-          null,
-          null,
-          [ 1, prefixAndFirstChar.length ],
+          startLine,
+          params.lines[startLine - 1],
+          true,
+          false,
+          [ startColumn, length ],
           {
-            "editColumn": prefixLengthNoSpace + 1,
-            "deleteCount": deleteCount
-          });
+            "editColumn": startColumn,
+            "deleteCount": length
+          }
+        );
       }
-    });
+    }
   }
 };
 
diff --git a/lib/md023.js b/lib/md023.js
index d3644b37..ec242f34 100644
--- a/lib/md023.js
+++ b/lib/md023.js
@@ -2,9 +2,8 @@
 
 "use strict";
 
-const { addErrorContext, filterTokens } = require("../helpers");
-
-const spaceBeforeHeadingRe = /^(\s+|[>\s]+\s\s)[^>\s]/;
+const { addErrorContext } = require("../helpers");
+const { filterByTypes } = require("../helpers/micromark.cjs");
 
 // eslint-disable-next-line jsdoc/valid-types
 /** @type import("./markdownlint").Rule */
@@ -12,30 +11,33 @@ module.exports = {
   "names": [ "MD023", "heading-start-left" ],
   "description": "Headings must start at the beginning of the line",
   "tags": [ "headings", "spaces" ],
-  "parser": "markdownit",
+  "parser": "micromark",
   "function": function MD023(params, onError) {
-    filterTokens(params, "heading_open", function forToken(token) {
-      const { lineNumber, line } = token;
-      const match = line.match(spaceBeforeHeadingRe);
-      if (match) {
-        const [ prefixAndFirstChar, prefix ] = match;
-        let deleteCount = prefix.length;
-        const prefixLengthNoSpace = prefix.trimEnd().length;
-        if (prefixLengthNoSpace) {
-          deleteCount -= prefixLengthNoSpace - 1;
-        }
+    const headings = filterByTypes(
+      params.parsers.micromark.tokens,
+      [ "atxHeading", "linePrefix", "setextHeading" ]
+    );
+    for (let i = 0; i < headings.length - 1; i++) {
+      if (
+        (headings[i].type === "linePrefix") &&
+        (headings[i + 1].type !== "linePrefix") &&
+        (headings[i].startLine === headings[i + 1].startLine)
+      ) {
+        const { endColumn, startColumn, startLine } = headings[i];
+        const length = endColumn - startColumn;
         addErrorContext(
           onError,
-          lineNumber,
-          line,
-          null,
-          null,
-          [ 1, prefixAndFirstChar.length ],
+          startLine,
+          params.lines[startLine - 1],
+          true,
+          false,
+          [ startColumn, length ],
           {
-            "editColumn": prefixLengthNoSpace + 1,
-            "deleteCount": deleteCount
-          });
+            "editColumn": startColumn,
+            "deleteCount": length
+          }
+        );
       }
-    });
+    }
   }
 };
diff --git a/test/headings_with_spaces_at_the_beginning.md b/test/headings_with_spaces_at_the_beginning.md
index f3e28ee9..0c677f7f 100644
--- a/test/headings_with_spaces_at_the_beginning.md
+++ b/test/headings_with_spaces_at_the_beginning.md
@@ -16,7 +16,7 @@ Some text
   ```
 
 * This is another case where MD023 shouldn't be triggered
-  # Test {MD022} {MD023} Valid heading for CommonMark (see section 5.2)
+  # Test {MD022} Valid heading for CommonMark (see section 5.2)
     # Test {MD022} {MD023} Also valid heading for CommonMark
 
 <!-- markdownlint-configure-file {
diff --git a/test/snapshots/markdownlint-test-scenarios.js.md b/test/snapshots/markdownlint-test-scenarios.js.md
index f0704f91..b9e3043d 100644
--- a/test/snapshots/markdownlint-test-scenarios.js.md
+++ b/test/snapshots/markdownlint-test-scenarios.js.md
@@ -623,7 +623,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: [
             1,
-            2,
+            1,
           ],
           fixInfo: {
             deleteCount: 1,
@@ -5602,12 +5602,12 @@ Generated by [AVA](https://avajs.dev).
           errorContext: '>  ## Quoted indented sub-head...',
           errorDetail: null,
           errorRange: [
+            3,
             1,
-            4,
           ],
           fixInfo: {
-            deleteCount: 3,
-            editColumn: 2,
+            deleteCount: 1,
+            editColumn: 3,
           },
           lineNumber: 17,
           ruleDescription: 'Headings must start at the beginning of the line',
@@ -5621,12 +5621,12 @@ Generated by [AVA](https://avajs.dev).
           errorContext: '  >  ## Quoted indented sub-he...',
           errorDetail: null,
           errorRange: [
+            5,
             1,
-            6,
           ],
           fixInfo: {
-            deleteCount: 3,
-            editColumn: 4,
+            deleteCount: 1,
+            editColumn: 5,
           },
           lineNumber: 33,
           ruleDescription: 'Headings must start at the beginning of the line',
@@ -7141,7 +7141,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: [
             1,
-            2,
+            1,
           ],
           fixInfo: {
             deleteCount: 1,
@@ -16650,7 +16650,7 @@ Generated by [AVA](https://avajs.dev).
     {
       errors: [
         {
-          errorContext: '# Test {MD022} {MD023} Valid heading for CommonMark (see section 5.2)',
+          errorContext: '# Test {MD022} Valid heading for CommonMark (see section 5.2)',
           errorDetail: 'Expected: 1; Actual: 0; Above',
           errorRange: null,
           fixInfo: {
@@ -16666,7 +16666,7 @@ Generated by [AVA](https://avajs.dev).
           ],
         },
         {
-          errorContext: '# Test {MD022} {MD023} Valid heading for CommonMark (see section 5.2)',
+          errorContext: '# Test {MD022} Valid heading for CommonMark (see section 5.2)',
           errorDetail: 'Expected: 1; Actual: 0; Below',
           errorRange: null,
           fixInfo: {
@@ -16703,7 +16703,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: [
             1,
-            2,
+            1,
           ],
           fixInfo: {
             deleteCount: 1,
@@ -16722,7 +16722,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: [
             1,
-            2,
+            1,
           ],
           fixInfo: {
             deleteCount: 1,
@@ -16741,7 +16741,7 @@ Generated by [AVA](https://avajs.dev).
           errorDetail: null,
           errorRange: [
             1,
-            2,
+            1,
           ],
           fixInfo: {
             deleteCount: 1,
@@ -16755,35 +16755,16 @@ Generated by [AVA](https://avajs.dev).
             'heading-start-left',
           ],
         },
-        {
-          errorContext: '  # Test {MD022} {MD023} Valid...',
-          errorDetail: null,
-          errorRange: [
-            1,
-            3,
-          ],
-          fixInfo: {
-            deleteCount: 2,
-            editColumn: 1,
-          },
-          lineNumber: 19,
-          ruleDescription: 'Headings must start at the beginning of the line',
-          ruleInformation: 'https://github.com/DavidAnson/markdownlint/blob/v0.0.0/doc/md023.md',
-          ruleNames: [
-            'MD023',
-            'heading-start-left',
-          ],
-        },
         {
           errorContext: '    # Test {MD022} {MD023} Als...',
           errorDetail: null,
           errorRange: [
-            1,
-            5,
+            3,
+            2,
           ],
           fixInfo: {
-            deleteCount: 4,
-            editColumn: 1,
+            deleteCount: 2,
+            editColumn: 3,
           },
           lineNumber: 20,
           ruleDescription: 'Headings must start at the beginning of the line',
@@ -16813,9 +16794,9 @@ Generated by [AVA](https://avajs.dev).
       ␊
       * This is another case where MD023 shouldn't be triggered␊
       ␊
-      # Test {MD022} {MD023} Valid heading for CommonMark (see section 5.2)␊
+        # Test {MD022} Valid heading for CommonMark (see section 5.2)␊
       ␊
-      # Test {MD022} {MD023} Also valid heading for CommonMark␊
+        # Test {MD022} {MD023} Also valid heading for CommonMark␊
       ␊
       <!-- markdownlint-configure-file {␊
         "heading-style": false,␊
diff --git a/test/snapshots/markdownlint-test-scenarios.js.snap b/test/snapshots/markdownlint-test-scenarios.js.snap
index 7dda54c5..6674412d 100644
Binary files a/test/snapshots/markdownlint-test-scenarios.js.snap and b/test/snapshots/markdownlint-test-scenarios.js.snap differ