diff --git a/changelog.d/20231120_160115_regis_nightly_common_version.md b/changelog.d/20231120_160115_regis_nightly_common_version.md
new file mode 100644
index 0000000..4b5b0b3
--- /dev/null
+++ b/changelog.d/20231120_160115_regis_nightly_common_version.md
@@ -0,0 +1 @@
+- [Improvement] Do not hardcode `OPENEDX_COMMON_VERSION = master` in the nightly branch. This removes git conflicts whenever we bump the common version in the master branch. (by @regisb)
diff --git a/docs/configuration.rst b/docs/configuration.rst
index 9375da5..c8e4139 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -136,7 +136,7 @@ Open edX customisation
 
 This defines the git repository from which you install Open edX platform code. If you run an Open edX fork with custom patches, set this to your own git repository. You may also override this configuration parameter at build time, by providing a ``--build-arg`` option.
 
-- ``OPENEDX_COMMON_VERSION`` (default: ``"open-release/palm.4"``)
+- ``OPENEDX_COMMON_VERSION`` (default: ``"open-release/palm.4"``, or ``master`` in :ref:`nightly <nightly>`)
 
 This defines the default version that will be pulled from all Open edX git repositories.
 
diff --git a/tutor/config.py b/tutor/config.py
index d343394..2a0ee73 100644
--- a/tutor/config.py
+++ b/tutor/config.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 from copy import deepcopy
+import typing as t
 
 import os
 
@@ -138,13 +139,32 @@ def get_defaults() -> Config:
 
     Entries in this configuration are unrendered.
     """
-    defaults = get_template("defaults.yml")
-    for name, value in hooks.Filters.CONFIG_DEFAULTS.iterate():
-        defaults[name] = value
+    defaults = dict(hooks.Filters.CONFIG_DEFAULTS.iterate())
     update_with_env(defaults)
     return defaults
 
 
+@hooks.Filters.CONFIG_DEFAULTS.add(priority=hooks.priorities.HIGH)
+def _load_config_defaults_yml(
+    items: list[tuple[str, t.Any]]
+) -> list[tuple[str, t.Any]]:
+    defaults = get_template("defaults.yml")
+    items += list(defaults.items())
+    return items
+
+
+@hooks.Filters.CONFIG_DEFAULTS.add()
+def _set_openedx_common_version_in_nightly(
+    items: list[tuple[str, t.Any]]
+) -> list[tuple[str, t.Any]]:
+    # REMOVE-AFTER-v16 move this callback to the dedicated openedx/plugin.py module
+    from tutor.__about__ import __version_suffix__
+
+    if __version_suffix__ == "nightly":
+        items.append(("OPENEDX_COMMON_VERSION", "master"))
+    return items
+
+
 def get_template(filename: str) -> Config:
     """
     Get one of the configuration templates.
diff --git a/tutor/templates/config/defaults.yml b/tutor/templates/config/defaults.yml
index 1eb1bac..c753328 100644
--- a/tutor/templates/config/defaults.yml
+++ b/tutor/templates/config/defaults.yml
@@ -52,6 +52,7 @@ OPENEDX_CMS_UWSGI_WORKERS: 2
 OPENEDX_LMS_UWSGI_WORKERS: 2
 OPENEDX_MYSQL_DATABASE: "openedx"
 OPENEDX_MYSQL_USERNAME: "openedx"
+# the common version will be automatically set to "master" in the nightly branch
 OPENEDX_COMMON_VERSION: "open-release/palm.4"
 OPENEDX_EXTRA_PIP_REQUIREMENTS:
   - "openedx-scorm-xblock>=16.0.0,<17.0.0"