diff --git a/source/blender/blenloader/intern/versioning_userdef.c b/source/blender/blenloader/intern/versioning_userdef.c
index 6ca7bba1ed2..a55568129c5 100644
--- a/source/blender/blenloader/intern/versioning_userdef.c
+++ b/source/blender/blenloader/intern/versioning_userdef.c
@@ -39,8 +39,21 @@
 
 #include "BLO_readfile.h"  /* Own include. */
 
+/* Disallow access to global userdef. */
 #define U (_error_)
 
+#define USER_VERSION_ATLEAST(ver, subver) MAIN_VERSION_ATLEAST(userdef, ver, subver)
+
+static void do_versions_theme(UserDef *userdef, bTheme *btheme)
+{
+	if (!USER_VERSION_ATLEAST(280, 20)) {
+		memcpy(btheme, &U_theme_default, sizeof(*btheme));
+	}
+}
+
+#undef USER_VERSION_ATLEAST
+
+
 /* patching UserDef struct and Themes */
 void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
 {
@@ -323,4 +336,8 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
 #endif
 	/* this timer uses U */
 // XXX	reset_autosave();
+
+	for (bTheme *btheme = userdef->themes.first; btheme; btheme = btheme->next) {
+		do_versions_theme(userdef, btheme);
+	}
 }