diff --git a/source/blender/blenloader/BLO_readfile.h b/source/blender/blenloader/BLO_readfile.h
index 4571e50dd36..88d89d9d6da 100644
--- a/source/blender/blenloader/BLO_readfile.h
+++ b/source/blender/blenloader/BLO_readfile.h
@@ -228,7 +228,7 @@ void BLO_update_defaults_startup_blend(struct Main *bmain, const char *app_templ
 void BLO_update_defaults_workspace(struct WorkSpace *workspace, const char *app_template);
 
 /* Version patch user preferences. */
-void BLO_version_defaults_userpref_blend(struct Main *bmain, struct UserDef *userdef);
+void BLO_version_defaults_userpref_blend(struct UserDef *userdef);
 
 /* Disable unwanted experimental feature settings on startup. */
 void BLO_sanitize_experimental_features_userpref_blend(struct UserDef *userdef);
diff --git a/source/blender/blenloader/intern/versioning_userdef.c b/source/blender/blenloader/intern/versioning_userdef.c
index 691258a5a8c..0265bd85f14 100644
--- a/source/blender/blenloader/intern/versioning_userdef.c
+++ b/source/blender/blenloader/intern/versioning_userdef.c
@@ -303,10 +303,10 @@ static bool keymap_item_has_invalid_wm_context_data_path(wmKeyMapItem *kmi,
 }
 
 /* patching UserDef struct and Themes */
-void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
+void BLO_version_defaults_userpref_blend(UserDef *userdef)
 {
-
-#define USER_VERSION_ATLEAST(ver, subver) MAIN_VERSION_ATLEAST(bmain, ver, subver)
+  /* #UserDef & #Main happen to have the same struct member. */
+#define USER_VERSION_ATLEAST(ver, subver) MAIN_VERSION_ATLEAST(userdef, ver, subver)
 
   /* the UserDef struct is not corrected with do_versions() .... ugh! */
   if (userdef->wheellinescroll == 0) {
diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index 5fcde98f200..972c741f061 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -1752,7 +1752,7 @@ void UI_popup_handlers_remove_all(struct bContext *C, struct ListBase *handlers)
  * be used to reinitialize some internal state if user preferences change. */
 
 void UI_init(void);
-void UI_init_userdef(struct Main *bmain);
+void UI_init_userdef(void);
 void UI_reinit_font(void);
 void UI_exit(void);
 
diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 25354c30c62..d93d80bb4ef 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -7059,10 +7059,10 @@ void UI_init(void)
 }
 
 /* after reading userdef file */
-void UI_init_userdef(Main *bmain)
+void UI_init_userdef(void)
 {
   /* fix saved themes */
-  init_userdef_do_versions(bmain);
+  init_userdef_do_versions();
   uiStyleInit();
 
   BLO_sanitize_experimental_features_userpref_blend(&U);
diff --git a/source/blender/editors/interface/interface_intern.h b/source/blender/editors/interface/interface_intern.h
index 60d60102736..91a71b0ca28 100644
--- a/source/blender/editors/interface/interface_intern.h
+++ b/source/blender/editors/interface/interface_intern.h
@@ -996,7 +996,7 @@ void icon_draw_rect_input(
     float x, float y, int w, int h, float alpha, short event_type, short event_value);
 
 /* resources.c */
-void init_userdef_do_versions(struct Main *bmain);
+void init_userdef_do_versions(void);
 void ui_resources_init(void);
 void ui_resources_free(void);
 
diff --git a/source/blender/editors/interface/resources.c b/source/blender/editors/interface/resources.c
index 76ad3981586..1601d9914a3 100644
--- a/source/blender/editors/interface/resources.c
+++ b/source/blender/editors/interface/resources.c
@@ -1501,9 +1501,9 @@ void UI_make_axis_color(const uchar src_col[3], uchar dst_col[3], const char axi
 }
 
 /* patching UserDef struct and Themes */
-void init_userdef_do_versions(Main *bmain)
+void init_userdef_do_versions(void)
 {
-  BLO_version_defaults_userpref_blend(bmain, &U);
+  BLO_version_defaults_userpref_blend(&U);
 
   if (STREQ(U.tempdir, "/")) {
     BKE_tempdir_system_init(U.tempdir);
diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index 7382a784ae0..6e3a5ccb339 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -392,7 +392,7 @@ static void wm_window_match_do(bContext *C,
 static void wm_init_userdef(Main *bmain)
 {
   /* versioning is here */
-  UI_init_userdef(bmain);
+  UI_init_userdef();
 
   /* needed so loading a file from the command line respects user-pref T26156. */
   SET_FLAG_FROM_TEST(G.fileflags, U.flag & USER_FILENOUI, G_FILE_NO_UI);