diff --git a/MozillaFirefox.changes b/MozillaFirefox.changes
index 83bcba28..21e335eb 100644
--- a/MozillaFirefox.changes
+++ b/MozillaFirefox.changes
@@ -1,5 +1,5 @@
 -------------------------------------------------------------------
-Sat Dec 26 07:37:19 UTC 2015 - wr@rosenauer.org
+Tue Dec 29 20:29:35 UTC 2015 - wr@rosenauer.org
 
 - update to Firefox 43.0.3
   * requires NSS 3.20.2 to fix
@@ -10,6 +10,7 @@ Sat Dec 26 07:37:19 UTC 2015 - wr@rosenauer.org
   * workaround Youtube user agent detection issue (bmo#1233970)
 - fix file download regression for multi user systems
   (bmo#1233434) (mozilla-bmo1233434.patch)
+- explicitely requires libXcomposite-devel
 
 -------------------------------------------------------------------
 Sun Dec 13 23:07:56 UTC 2015 - wr@rosenauer.org
diff --git a/MozillaFirefox.spec b/MozillaFirefox.spec
index fd6e060f..b4da464f 100644
--- a/MozillaFirefox.spec
+++ b/MozillaFirefox.spec
@@ -69,6 +69,7 @@ BuildRequires:  autoconf213
 BuildRequires:  dbus-1-glib-devel
 BuildRequires:  fdupes
 BuildRequires:  gcc-c++
+BuildRequires:  libXcomposite-devel
 BuildRequires:  libcurl-devel
 BuildRequires:  libgnomeui-devel
 BuildRequires:  libidl-devel