diff --git a/.firefox.metadata b/.firefox.metadata
index 1863b73..2a97de3 100644
--- a/.firefox.metadata
+++ b/.firefox.metadata
@@ -1,5 +1,5 @@
 c822547dbc12e2baebdfdfb38b665e23f0c2513a SOURCES/cbindgen-vendor.tar.xz
-0d960c32727bbe7dd0b752a3d2165f429f4144b3 SOURCES/firefox-91.9.0esr.processed-source.tar.xz
-584306ac938eedb9e3ad93e5d23481b63478bbaf SOURCES/firefox-langpacks-91.9.0esr-20220426.tar.xz
+d13ae0300c2295a2762eeeea2556ca847e55799c SOURCES/firefox-91.9.1esr.processed-source.tar.xz
+253fb25c2ea809ca7505c4b164723038f2a5e718 SOURCES/firefox-langpacks-91.9.1esr-20220520.tar.xz
 b5fd1332d8e0d37339ae170c7bebcb63a40b22e0 SOURCES/nspr-4.32.0-1.el8_1.src.rpm
 8fff814901e03c2518ede2f8992d898f5ba61ed9 SOURCES/nss-3.67.0-7.el8_1.src.rpm
diff --git a/.gitignore b/.gitignore
index 10cd3a7..5d36065 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 SOURCES/cbindgen-vendor.tar.xz
-SOURCES/firefox-91.9.0esr.processed-source.tar.xz
-SOURCES/firefox-langpacks-91.9.0esr-20220426.tar.xz
+SOURCES/firefox-91.9.1esr.processed-source.tar.xz
+SOURCES/firefox-langpacks-91.9.1esr-20220520.tar.xz
 SOURCES/nspr-4.32.0-1.el8_1.src.rpm
 SOURCES/nss-3.67.0-7.el8_1.src.rpm
diff --git a/SPECS/firefox.spec b/SPECS/firefox.spec
index e71f97d..5967a36 100644
--- a/SPECS/firefox.spec
+++ b/SPECS/firefox.spec
@@ -127,9 +127,16 @@ end}
 %global official_branding       1
 %global build_langpacks         1
 
+# Workaround the dreaded "upstream source file changed content" rpmdiff failure that only secalert can waive.
+# If set to .b2 or .b3 ... the processed source file needs to be renamed before upload, e.g.
+# firefox-91.9.0esr.b2.processed-source.tar.xz
+# With does_not_exist it's empty and source file name as is.
+#global buildnum %{?does_not_exist}
+%global buildnum %{?does_not_exist}
+
 Summary:        Mozilla Firefox Web browser
 Name:           firefox
-Version:        91.9.0
+Version:        91.9.1
 Release:        1%{?dist}
 URL:            https://www.mozilla.org/firefox/
 License:        MPLv1.1 or GPLv2+ or LGPLv2+
@@ -152,9 +159,9 @@ ExcludeArch:    aarch64 s390 ppc
 # The official tarball has to be always processed by the process-official-tarball
 # script.
 # Link to official tarball: https://hg.mozilla.org/releases/mozilla-release/archive/firefox-%%{version}%%{?pre_version}.source.tar.xz
-Source0:        firefox-%{version}%{?pre_version}.processed-source.tar.xz
+Source0:        firefox-%{version}%{?pre_version}%{?buildnum}.processed-source.tar.xz
 %if %{build_langpacks}
-Source1:        firefox-langpacks-%{version}%{?pre_version}-20220426.tar.xz
+Source1:        firefox-langpacks-%{version}%{?pre_version}-20220520.tar.xz
 
 %endif
 Source2:        cbindgen-vendor.tar.xz
@@ -1261,9 +1268,12 @@ gtk-update-icon-cache %{_datadir}/icons/hicolor &>/dev/null || :
 #---------------------------------------------------------------------
 
 %changelog
-* Wed May 18 2022 Eduard Abdullin <eabdullin@almalinux.org> - 91.9.0-1.alma
+* Thu May 26 2022 Eduard Abdullin <eabdullin@almalinux.org> - 91.9.1-1.alma
 - Debrand for AlmaLinux
 
+* Fri May 20 2022 Jan Horak <jhorak@redhat.com> - 91.9.1-1
+- Update to 91.9.1 build1
+
 * Tue Apr 26 2022 Eike Rathke <erack@redhat.com> - 91.9.0-1
 - Update to 91.9.0