diff --git a/src/rules.ts b/src/rules.ts
index cc2e62bccf..04d58f222c 100644
--- a/src/rules.ts
+++ b/src/rules.ts
@@ -285,6 +285,13 @@ const _notPunctuationOrSpace = /[^\s\p{P}\p{S}]/u;
 const punctuation = edit(/^((?![*_])punctSpace)/, 'u')
   .replace(/punctSpace/g, _punctuationOrSpace).getRegex();
 
+/** Quote chars for pedantic rule 6 lookbehind; includes both straight and curly forms. */
+const closeQuoteClass = '["\u201c\u201d\u2018\u2019\']';
+/** Quote chars excluded from pedantic left-delim captured punct so `**"` / `**'` yields an empty nextChar. */
+const openQuoteClass = '["\'\u2018\u2019\u201c]';
+/** When lookbehind is supported, pedantic rule 6 does not match immediately after a quote (e.g. `"**` in `**"A"**`). */
+const closeQuoteLookbehind = supportsLookbehind ? `(?<!${closeQuoteClass})` : '';
+
 // GFM allows ~ inside strong and em for strikethrough
 const _punctuationGfmStrongEm = /(?!~)[\p{P}\p{S}]/u;
 const _punctuationOrSpaceGfmStrongEm = /(?!~)[\s\p{P}\p{S}]/u;
@@ -308,6 +315,14 @@ const emStrongLDelimGfm = edit(emStrongLDelimCore, 'u')
   .replace(/punct/g, _punctuationGfmStrongEm)
   .getRegex();
 
+// Pedantic: do not treat a quote as left-delim punct (pairs with pedantic emStrongRDelim rule 6).
+const emStrongLDelimPedanticCore = /^(?:\*+(?:((?!\*)(?!openQuote)punct)|([^\s*]))?)|^_+(?:((?!_)(?!openQuote)punct)|([^\s_]))?/;
+
+const emStrongLDelimPedantic = edit(emStrongLDelimPedanticCore, 'u')
+  .replace(/openQuote/g, openQuoteClass)
+  .replace(/punct/g, _punctuation)
+  .getRegex();
+
 const emStrongRDelimAstCore =
   '^[^_*]*?__[^_*]*?\\*[^_*]*?(?=__)' // Skip orphan inside strong
 + '|[^*]+(?=[^*])' // Consume to delim
@@ -330,7 +345,25 @@ const emStrongRDelimAstGfm = edit(emStrongRDelimAstCore, 'gu')
   .replace(/punct/g, _punctuationGfmStrongEm)
   .getRegex();
 
-// (6) Not allowed for _
+// Pedantic: rule 3 requires whitespace before left delim; rule 6 allows punct before close (e.g. `:**bar`).
+const emStrongRDelimAstPedanticCore =
+  '^[^_*]*?__[^_*]*?\\*[^_*]*?(?=__)' // Skip orphan inside strong
++ '|[^*]+(?=[^*])' // Consume to delim
++ '|(?!\\*)punct(\\*+)(?=[\\s]|$)' // (1) #*** can only be a Right Delimiter
++ '|notPunctSpace(\\*+)(?!\\*)(?=punctSpace|$)' // (2) a***#, a*** can only be a Right Delimiter
++ '|(?!\\*)[\\s](\\*+)(?=notPunctSpace)' // (3) ***a can only be Left Delimiter (whitespace required; not #***a)
++ '|[\\s](\\*+)(?!\\*)(?=punct)' // (4) ***# can only be Left Delimiter
++ '|(?!\\*)punct(\\*+)(?!\\*)(?=punct)' // (5) #***# can be either Left or Right Delimiter
++ '|closeQuoteLookbehind(?:(?!\\*)punct|notPunctSpace)(\\*+)(?!\\*)(?=notPunctSpace)'; // (6) a***a, #***a, and :** (e.g. **foo:**bar)
+
+const emStrongRDelimAstPedantic = edit(emStrongRDelimAstPedanticCore, 'gu')
+  .replace(/closeQuoteLookbehind/g, closeQuoteLookbehind)
+  .replace(/notPunctSpace/g, _notPunctuationOrSpace)
+  .replace(/punctSpace/g, _punctuationOrSpace)
+  .replace(/punct/g, _punctuation)
+  .getRegex();
+
+// Normal: no rule 6 for _ (a___a cannot close as emphasis).
 const emStrongRDelimUnd = edit(
   '^[^_*]*?\\*\\*[^_*]*?_[^_*]*?(?=\\*\\*)' // Skip orphan inside strong
 + '|[^_]+(?=[^_])' // Consume to delim
@@ -344,6 +377,24 @@ const emStrongRDelimUnd = edit(
   .replace(/punct/g, _punctuation)
   .getRegex();
 
+// Pedantic: same rule 3/6 adjustments as emStrongRDelimAstPedantic (e.g. `_foo:_bar`).
+const emStrongRDelimUndPedanticCore =
+  '^[^_*]*?\\*\\*[^_*]*?_[^_*]*?(?=\\*\\*)' // Skip orphan inside strong
++ '|[^_]+(?=[^_])' // Consume to delim
++ '|(?!_)punct(_+)(?=[\\s]|$)' // (1) #___ can only be a Right Delimiter
++ '|notPunctSpace(_+)(?!_)(?=punctSpace|$)' // (2) a___#, a___ can only be a Right Delimiter
++ '|(?!_)[\\s](_+)(?=notPunctSpace)' // (3) ___a can only be Left Delimiter (whitespace required; not #___a)
++ '|[\\s](_+)(?!_)(?=punct)' // (4) ___# can only be Left Delimiter
++ '|(?!_)punct(_+)(?!_)(?=punct)' // (5) #___# can be either Left or Right Delimiter
++ '|closeQuoteLookbehind(?:(?!_)punct|notPunctSpace)(_+)(?!_)(?=notPunctSpace)'; // (6) a___a, #___a, and :__ (e.g. _foo:_bar)
+
+const emStrongRDelimUndPedantic = edit(emStrongRDelimUndPedanticCore, 'gu')
+  .replace(/closeQuoteLookbehind/g, closeQuoteLookbehind)
+  .replace(/notPunctSpace/g, _notPunctuationOrSpace)
+  .replace(/punctSpace/g, _punctuationOrSpace)
+  .replace(/punct/g, _punctuation)
+  .getRegex();
+
 // Tilde left delimiter for strikethrough (similar to emStrongLDelim for asterisk)
 const delLDelim = edit(/^~~?(?:((?!~)punct)|[^\s~])/, 'u')
   .replace(/punct/g, _punctuation)
@@ -446,6 +497,9 @@ type InlineKeys = keyof typeof inlineNormal;
 
 const inlinePedantic: Record<InlineKeys, RegExp> = {
   ...inlineNormal,
+  emStrongLDelim: emStrongLDelimPedantic,
+  emStrongRDelimAst: emStrongRDelimAstPedantic,
+  emStrongRDelimUnd: emStrongRDelimUndPedantic,
   link: edit(/^!?\[(label)\]\((.*?)\)/)
     .replace('label', _inlineLabel)
     .getRegex(),
diff --git a/test/specs/original/strong_punctuation.html b/test/specs/original/strong_punctuation.html
new file mode 100644
index 0000000000..ceac387649
--- /dev/null
+++ b/test/specs/original/strong_punctuation.html
@@ -0,0 +1,15 @@
+<p><strong>foo:</strong>bar</p>
+
+<p><strong>foo</strong>bar</p>
+
+<p><em>foo:</em>bar</p>
+
+<p><em>foo:</em>bar</p>
+
+<p><strong>foo:</strong>bar</p>
+
+<p>aa<strong>&quot;A&quot;</strong>and<strong>&quot;B&quot;</strong>aa</p>
+
+<p>aa<strong>&#39;A&#39;</strong>and<strong>&#39;B&#39;</strong>aa</p>
+
+<p>We can compare <strong>&quot;direction&quot;</strong> and <strong>&quot;distance&quot;</strong> in two ways</p>
diff --git a/test/specs/original/strong_punctuation.md b/test/specs/original/strong_punctuation.md
new file mode 100644
index 0000000000..d6a4c453eb
--- /dev/null
+++ b/test/specs/original/strong_punctuation.md
@@ -0,0 +1,19 @@
+---
+pedantic: true
+---
+
+**foo:**bar
+
+**foo**bar
+
+*foo:*bar
+
+_foo:_bar
+
+__foo:__bar
+
+aa**"A"**and**"B"**aa
+
+aa**'A'**and**'B'**aa
+
+We can compare **"direction"** and **"distance"** in two ways