--- a/setup.py	Fri Sep 19 12:05:57 2025 +0200
+++ b/setup.py	Fri Sep 19 12:40:07 2025 +0200
@@ -1367,6 +1367,12 @@
         # We can't pip install pytest on pyodide, so specify it here.
         requires_dist.append('pytest')
 
+    #
+    # We need packaging because of extended version parsing (including local
+    # version specifiers.
+    #
+    requires_dist.append('packaging')
+
     p = pipcl.Package(
             name,
             version,

--- a/src/__init__.py	Fri Sep 19 12:05:57 2025 +0200
+++ b/src/__init__.py	Fri Sep 19 12:40:07 2025 +0200
@@ -17,6 +17,7 @@
 import os
 import pathlib
 import glob
+import packaging.version
 import re
 import string
 import sys
@@ -366,12 +367,8 @@
 
 def _int_rc(text):
     '''
-    Converts string to int, ignoring trailing 'rc...' and a trailing
-    local version.
-    '''
-    rc = text.find('+')
-    if rc >= 0:
-        text = text[:rc]
+    Converts string to int, ignoring trailing 'rc...'.
+    '''
     rc = text.find('rc')
     if rc >= 0:
         text = text[:rc]
@@ -397,8 +394,8 @@
 
 # Versions as tuples; useful when comparing versions.
 #
-pymupdf_version_tuple = tuple( [_int_rc(i) for i in pymupdf_version.split('.')])
-mupdf_version_tuple = tuple( [_int_rc(i) for i in mupdf_version.split('.')])
+pymupdf_version_tuple = packaging.version.Version(pymupdf_version).release
+mupdf_version_tuple = packaging.version.Version(mupdf_version).release
 
 assert mupdf_version_tuple == (mupdf.FZ_VERSION_MAJOR, mupdf.FZ_VERSION_MINOR, mupdf.FZ_VERSION_PATCH), \
         f'Inconsistent MuPDF version numbers: {mupdf_version_tuple=} != {(mupdf.FZ_VERSION_MAJOR, mupdf.FZ_VERSION_MINOR, mupdf.FZ_VERSION_PATCH)=}'