diff --git a/srcpkgs/gst-libav/template b/srcpkgs/gst-libav/template
index 0ba6f6128e..0d7bf6057e 100644
--- a/srcpkgs/gst-libav/template
+++ b/srcpkgs/gst-libav/template
@@ -1,7 +1,7 @@
 # Template file for 'gst-libav'
 pkgname=gst-libav
 version=1:1.4.5
-revision=2
+revision=3
 lib32disabled=yes
 wrksrc="${pkgname}-${version#*:}"
 build_style=gnu-configure
@@ -15,3 +15,6 @@ license="GPL-2"
 homepage="http://gstreamer.freedesktop.org"
 distfiles="${homepage}/src/${pkgname}/${pkgname}-${version#*:}.tar.xz"
 checksum=605c62624604f3bb5c870844cc1f2711779cc533b004c2aa1d8c0d58557afbbc
+
+# Required by musl for M_SQRT1_2
+CFLAGS="-D_XOPEN_SOURCE"