diff --git a/thunderbird.spec b/thunderbird.spec
index ada4839..dd55c39 100644
--- a/thunderbird.spec
+++ b/thunderbird.spec
@@ -34,9 +34,15 @@
 %endif
 
 %define libnotify_version 0.4
-%global libvpx_version 1.3.0
 %define _default_patch_fuzz 2
 
+# Use system libvpx?
+%if 0%{?fedora} > 22
+%define system_libvpx      1
+%else
+%define system_libvpx      0
+%endif
+
 %define thunderbird_app_id \{3550f703-e582-4d05-9a08-453d09bdfdc6\} 
 # Bump one with each minor lightning release
 %define gdata_version 2.6
@@ -154,6 +160,7 @@ BuildRequires:  pulseaudio-libs-devel
 BuildRequires:  libicu-devel
 BuildRequires:  GConf2-devel
 Requires:       mozilla-filesystem
+BuildRequires:  yasm
 Obsoletes:      thunderbird-lightning
 Provides:       thunderbird-lightning
 
@@ -300,6 +307,12 @@ echo "ac_add_options --disable-yarr-jit" >> .mozconfig
 echo "ac_add_options --disable-ion" >> .mozconfig
 %endif
 
+%if %{?system_libvpx}
+echo "ac_add_options --with-system-libvpx" >> .mozconfig
+%else
+echo "ac_add_options --without-system-libvpx" >> .mozconfig
+%endif
+
 # install lightning langpacks
 cd ..
 %{__tar} xf %{SOURCE2}