diff --git a/empty_dbbackend.diff b/empty_dbbackend.diff
new file mode 100644
index 0000000..12e3175
--- /dev/null
+++ b/empty_dbbackend.diff
@@ -0,0 +1,20 @@
+--- ./lib/backend/dbi.c.orig	2020-11-18 09:37:08.314743771 +0000
++++ ./lib/backend/dbi.c	2020-11-18 09:42:34.025792074 +0000
+@@ -77,7 +77,7 @@ dbDetectBackend(rpmdb rdb)
+ 	}
+     }
+ 
+-    if (!cfg) {
++    if (!cfg && (rdb->db_flags & RPMDB_FLAG_REBUILD) != 0) {
+ 	rpmlog(RPMLOG_WARNING, _("invalid %%_db_backend: %s\n"), db_backend);
+ 	goto exit;
+     }
+@@ -97,7 +97,7 @@ dbDetectBackend(rpmdb rdb)
+ 		rpmlog(RPMLOG_WARNING,
+ 			_("Converting database from %s to %s backend\n"),
+ 			ondisk->name, cfg->name);
+-	    } else {
++	    } else if (*db_backend) {
+ 		rpmlog(RPMLOG_WARNING,
+ 		    _("Found %s %s database while attempting %s backend: "
+ 		    "using %s backend.\n"),
diff --git a/rpm.changes b/rpm.changes
index 24879ca..b866450 100644
--- a/rpm.changes
+++ b/rpm.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Wed Nov 18 10:46:03 CET 2020 - mls@suse.de
+
+- allow opening the rpm database with an unset db_backend
+  * new patch: empty_dbbackend.diff
+
 -------------------------------------------------------------------
 Tue Oct 27 10:08:05 CET 2020 - Callum Farmer <callumjfarmer13@gmail.com>
 
diff --git a/rpm.spec b/rpm.spec
index 10f13c7..1b64d32 100644
--- a/rpm.spec
+++ b/rpm.spec
@@ -127,6 +127,7 @@ Patch117:       findsupplements.diff
 Patch122:       db_conversion.diff
 Patch123:       nextiteratorheaderblob.diff
 Patch127:       finddebuginfo-check-res-file.patch
+Patch128:       empty_dbbackend.diff
 Patch6464:      auto-config-update-aarch64-ppc64le.diff
 BuildRoot:      %{_tmppath}/%{name}-%{version}-build
 #
@@ -251,7 +252,7 @@ cp config.guess config.sub db/dist/
 %patch                   -P 93 -P 94                         -P 99
 %patch -P 100        -P 102 -P 103
 %patch -P 109                                           -P 117
-%patch -P 122 -P 123 -P 127
+%patch -P 122 -P 123 -P 127 -P 128
 
 %ifarch aarch64 ppc64le riscv64
 %patch6464