diff --git a/scripts/g.extension/g.extension.py b/scripts/g.extension/g.extension.py
index d72d6a6075b..8e1be707c9b 100644
--- a/scripts/g.extension/g.extension.py
+++ b/scripts/g.extension/g.extension.py
@@ -144,7 +144,6 @@
 # TODO: solve addon-extension(-module) confusion
 
 import fileinput
-import http
 import os
 import codecs
 import sys
@@ -188,7 +187,6 @@
 HEADERS = {
     "User-Agent": "Mozilla/5.0",
 }
-HTTP_STATUS_CODES = list(http.HTTPStatus)
 GIT_URL = "https://github.com/OSGeo/grass-addons/"
 
 # MAKE command
@@ -258,7 +256,7 @@ def _get_version(self):
         git_version, stderr = git_version.communicate()
         if stderr:
             gs.fatal(
-                _("Failed to get Git version.\n{error}").format(
+                _("Failed to get Git version.\n{}").format(
                     gs.decode(stderr),
                 )
             )
@@ -504,23 +502,27 @@ def get_version_branch(major_version):
     if not, take branch for the previous version
     For the official repo we assume that at least one version branch is present"""
     version_branch = f"grass{major_version}"
-    branch = gs.Popen(
-        ["git", "ls-remote", "--heads", GIT_URL, f"refs/heads/{version_branch}"],
-        stdout=PIPE,
-        stderr=PIPE,
-    )
-    branch, stderr = branch.communicate()
-    if stderr:
-        gs.fatal(
-            _(
-                "Failed to get branch from the Git repository <{repo_path}>.\n"
-                "{error}"
-            ).format(
-                repo_path=GIT_URL,
-                error=gs.decode(stderr),
-            )
+    if sys.platform == "win32":
+        return version_branch
+    else:
+        branch = gs.Popen(
+            ["git", "ls-remote", "--heads", GIT_URL, f"refs/heads/{version_branch}"],
+            stdout=PIPE,
+            stderr=PIPE,
         )
-    if version_branch not in gs.decode(branch):
+        branch, stderr = branch.communicate()
+        if stderr:
+            gs.fatal(
+                _(
+                    "Failed to get branch from the Git repository <{repo_path}>.\n"
+                    "{error}"
+                ).format(
+                    repo_path=GIT_URL,
+                    error=gs.decode(stderr),
+                )
+            )
+        branch = gs.decode(branch)
+    if version_branch not in branch:
         version_branch = "grass{}".format(int(major_version) - 1)
     return version_branch
 
@@ -1147,7 +1149,7 @@ def write_xml_toolboxes(name, tree=None):
     file_.close()
 
 
-def install_extension(source, url, xmlurl, branch):
+def install_extension(source=None, url=None, xmlurl=None, branch=None):
     """Install extension (e.g. one module) or a toolbox (list of modules)"""
     gisbase = os.getenv("GISBASE")
     if not gisbase:
@@ -1514,11 +1516,12 @@ def install_module_xml(mlist):
     # read XML file
     tree = etree_fromfile(xml_file)
 
-    # Filter multi-addon addons
-    if len(mlist) > 1:
-        mlist = filter_multi_addon_addons(
-            mlist.copy()
-        )  # mlist.copy() keep the original list of add-ons
+    if sys.platform != "win32":
+        # Filter multi-addon addons
+        if len(mlist) > 1:
+            mlist = filter_multi_addon_addons(
+                mlist.copy()
+            )  # mlist.copy() keep the original list of add-ons
 
     # update tree
     for name in mlist:
@@ -2412,11 +2415,12 @@ def update_manual_page(module):
     # find URIs
     pattern = r"""<a href="([^"]+)">([^>]+)</a>"""
     addons = get_installed_extensions(force=True)
-    # Multi-addon
-    if len(addons) > 1:
-        for a in get_multi_addon_addons_which_install_only_html_man_page():
-            # Add multi-addon addons which install only manual html page
-            addons.append(a)
+    if sys.platform != "win32":
+        # Multi-addon
+        if len(addons) > 1:
+            for a in get_multi_addon_addons_which_install_only_html_man_page():
+                # Add multi-addon addons which install only manual html page
+                addons.append(a)
 
     for match in re.finditer(pattern, shtml):
         if match.group(1)[:4] == "http":
@@ -2825,17 +2829,23 @@ def main():
 
     if options["operation"] == "add":
         check_dirs()
-        if original_url == "" or flags["o"]:
-            """
-            Query GitHub API only if extension will be downloaded
-            from official GRASS GIS addon repository
-            """
-            get_addons_paths(gg_addons_base_dir=options["prefix"])
-        source, url = resolve_source_code(
-            name=options["extension"], url=original_url, branch=branch, fork=flags["o"]
-        )
-        xmlurl = resolve_xmlurl_prefix(original_url, source=source)
-        install_extension(source=source, url=url, xmlurl=xmlurl, branch=branch)
+        if sys.platform == "win32":
+            install_extension()
+        else:
+            if original_url == "" or flags["o"]:
+                """
+                Query GitHub API only if extension will be downloaded
+                from official GRASS GIS addon repository
+                """
+                get_addons_paths(gg_addons_base_dir=options["prefix"])
+            source, url = resolve_source_code(
+                name=options["extension"],
+                url=original_url,
+                branch=branch,
+                fork=flags["o"],
+            )
+            xmlurl = resolve_xmlurl_prefix(original_url, source=source)
+            install_extension(source=source, url=url, xmlurl=xmlurl, branch=branch)
     else:  # remove
         remove_extension(force=flags["f"])