diff --git a/srcpkgs/firefox/patches/ply-python3.11.patch b/srcpkgs/firefox/patches/ply-python3.11.patch
new file mode 100644
index 00000000000..8d1415a4b36
--- /dev/null
+++ b/srcpkgs/firefox/patches/ply-python3.11.patch
@@ -0,0 +1,85 @@
+The Ply lexer, which doesn't seem too active a project, wraps regular
+expressions from grammar definitions in its own regular expressions that name
+groups. This breaks re.compile in Python >= 3.11 when the original expressions
+contain global flags, because the compiler requires that global flags appear at
+the start of the expression instead of inside the named group.
+
+This patch wraps re.compile to scan the expression for any global flags and,
+when found, moves them to the start of the expression.
+
+--- a/third_party/python/ply/ply/lex.py
++++ b/third_party/python/ply/ply/lex.py
+@@ -49,6 +49,37 @@
+     # Python 3.0
+     StringTypes = (str, bytes)
+ 
++
++def _re_compile(expression, *args, **kwargs):
++    '''
++    Rearrange global flags in the regular expression to appear at the
++    beginning, avoiding deprecation warnings on Python < 3.11 and hard
++    errors on Python >= 3.11.
++    '''
++    flags = set()
++    remainder = ''
++
++    pattern = re.compile(r'\(\?([aiLmsux]+)\)')
++    while m := pattern.search(expression):
++        # Location of the global flag spec
++        l, h = m.span(0)
++        # Accumulate global flags from this spec
++        flags.update(m.group(1))
++        # Capture all text leading up to the match
++        remainder += expression[:l]
++        # Trim to the end fo the flag spec
++        expression = expression[h:]
++
++    # Any remaining expression contains no flags
++    remainder += expression
++
++    # If there are flags, they belong at the beginning
++    if flags:
++        remainder = f'(?{"".join(sorted(flags))})' + remainder
++
++    return re.compile(remainder, *args, **kwargs)
++
++
+ # This regular expression is used to match valid token names
+ _is_identifier = re.compile(r'^[a-zA-Z0-9_]+$')
+ 
+@@ -230,7 +261,7 @@
+             titem = []
+             txtitem = []
+             for pat, func_name in lre:
+-                titem.append((re.compile(pat, lextab._lexreflags), _names_to_funcs(func_name, fdict)))
++                titem.append((_re_compile(pat, lextab._lexreflags), _names_to_funcs(func_name, fdict)))
+ 
+             self.lexstatere[statename] = titem
+             self.lexstateretext[statename] = txtitem
+@@ -495,7 +526,7 @@
+         return []
+     regex = '|'.join(relist)
+     try:
+-        lexre = re.compile(regex, reflags)
++        lexre = _re_compile(regex, reflags)
+ 
+         # Build the index to function map for the matching engine
+         lexindexfunc = [None] * (max(lexre.groupindex.values()) + 1)
+@@ -758,7 +789,7 @@
+                     continue
+ 
+                 try:
+-                    c = re.compile('(?P<%s>%s)' % (fname, _get_regex(f)), self.reflags)
++                    c = _re_compile('(?P<%s>%s)' % (fname, _get_regex(f)), self.reflags)
+                     if c.match(''):
+                         self.log.error("%s:%d: Regular expression for rule '%s' matches empty string", file, line, f.__name__)
+                         self.error = True
+@@ -782,7 +813,7 @@
+                     continue
+ 
+                 try:
+-                    c = re.compile('(?P<%s>%s)' % (name, r), self.reflags)
++                    c = _re_compile('(?P<%s>%s)' % (name, r), self.reflags)
+                     if (c.match('')):
+                         self.log.error("Regular expression for rule '%s' matches empty string", name)
+                         self.error = True