diff --git a/lib/markdown2.py b/lib/markdown2.py
index 8b99ec3d..3f7e4b87 100755
--- a/lib/markdown2.py
+++ b/lib/markdown2.py
@@ -3003,7 +3003,8 @@ def __init__(self, md, options):
 
     def sub(self, match: re.Match) -> str:
         syntax = match.group(1)
-        text: str = match.string[match.start(): match.end()]
+        # use match.regs because strong/em regex may include preceding text in the match as well
+        text: str = match.string[match.regs[1][0]: match.end()]
         if '_' in syntax:
             # if using _this_ syntax, hash it to avoid processing, but don't hash the contents incase of nested syntax
             text = text.replace(syntax, _hash_text(self.name + syntax))
diff --git a/test/tm-cases/code_friendly_issue646.html b/test/tm-cases/code_friendly_issue646.html
new file mode 100644
index 00000000..5c8e0779
--- /dev/null
+++ b/test/tm-cases/code_friendly_issue646.html
@@ -0,0 +1 @@
+<p>A_<strong>B</strong></p>
diff --git a/test/tm-cases/code_friendly_issue646.opts b/test/tm-cases/code_friendly_issue646.opts
new file mode 100644
index 00000000..245e9828
--- /dev/null
+++ b/test/tm-cases/code_friendly_issue646.opts
@@ -0,0 +1 @@
+{"extras":["code-friendly"]}
\ No newline at end of file
diff --git a/test/tm-cases/code_friendly_issue646.text b/test/tm-cases/code_friendly_issue646.text
new file mode 100644
index 00000000..8f94c786
--- /dev/null
+++ b/test/tm-cases/code_friendly_issue646.text
@@ -0,0 +1 @@
+A_**B**
\ No newline at end of file