diff --git a/srcpkgs/libaom/patches/libaom-3.4.0-posix-c-source-ftello.patch b/srcpkgs/libaom/patches/libaom-3.4.0-posix-c-source-ftello.patch
new file mode 100644
index 00000000000..6e910b3f732
--- /dev/null
+++ b/srcpkgs/libaom/patches/libaom-3.4.0-posix-c-source-ftello.patch
@@ -0,0 +1,13 @@
+https://bugs.gentoo.org/869419
+
+POSIX_C_SOURCE is needed for ftello.
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -266,6 +266,7 @@ add_library(aom_rtcd OBJECT ${AOM_RTCD_SOURCES})
+ add_dependencies(aom_rtcd aom_version)
+ 
+ if(ENABLE_EXAMPLES)
++  add_definitions(-D_POSIX_C_SOURCE=200112L)
+   add_library(aom_encoder_stats OBJECT ${AOM_ENCODER_STATS_SOURCES})
+   set(AOM_LIB_TARGETS ${AOM_LIB_TARGETS} aom_encoder_stats)
+ endif()
diff --git a/srcpkgs/libaom/template b/srcpkgs/libaom/template
index 3b9e3c97cd3..7aa0cfb954e 100644
--- a/srcpkgs/libaom/template
+++ b/srcpkgs/libaom/template
@@ -1,7 +1,7 @@
 # Template file for 'libaom'
 pkgname=libaom
 version=3.8.1
-revision=1
+revision=2
 create_wrksrc=yes
 build_style=cmake
 configure_args="-DENABLE_DOCS=OFF -DBUILD_SHARED_LIBS=ON"