diff --git a/thirdparty/rexglue-sdk/thirdparty/CMakeLists.txt b/thirdparty/rexglue-sdk/thirdparty/CMakeLists.txt
index 05884256..ff7906f0 100644
--- a/thirdparty/rexglue-sdk/thirdparty/CMakeLists.txt
+++ b/thirdparty/rexglue-sdk/thirdparty/CMakeLists.txt
@@ -340,6 +340,7 @@ endfunction()
 set(FFMPEG_OVERLAY_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ffmpeg-overlay")
 set(FFMPEG_OVERLAY_BUILD_DIR "${CMAKE_CURRENT_BINARY_DIR}/ffmpeg-overlay")
 file(MAKE_DIRECTORY "${FFMPEG_OVERLAY_BUILD_DIR}/libavcodec")
+file(MAKE_DIRECTORY "${FFMPEG_OVERLAY_BUILD_DIR}/libavutil")
 configure_file(
   "${FFMPEG_OVERLAY_SRC_DIR}/codec_list.c" "${FFMPEG_OVERLAY_BUILD_DIR}/libavcodec/codec_list.c"
   COPYONLY
@@ -352,6 +353,20 @@ configure_file(
   "${FFMPEG_OVERLAY_SRC_DIR}/bsf_list.c" "${FFMPEG_OVERLAY_BUILD_DIR}/libavcodec/bsf_list.c"
   COPYONLY
 )
+file(WRITE "${FFMPEG_OVERLAY_BUILD_DIR}/libavutil/avconfig.h" [=[
+/* Generated by ReXGlue CMake for vendored FFmpeg */
+#ifndef AVUTIL_AVCONFIG_H
+#define AVUTIL_AVCONFIG_H
+#define AV_HAVE_BIGENDIAN 0
+#define AV_HAVE_FAST_UNALIGNED 1
+#endif /* AVUTIL_AVCONFIG_H */
+]=])
+file(WRITE "${FFMPEG_OVERLAY_BUILD_DIR}/libavutil/ffversion.h" [=[
+#ifndef AVUTIL_FFVERSION_H
+#define AVUTIL_FFVERSION_H
+#define FFMPEG_VERSION "xenia-premake"
+#endif /* AVUTIL_FFVERSION_H */
+]=])
 
 # Common defines for both libraries
 set(FFMPEG_COMMON_DEFINES
@@ -479,6 +494,8 @@ if(IS_ARM64)
     )
 endif()
 
+target_include_directories(libavutil BEFORE PRIVATE "${FFMPEG_OVERLAY_BUILD_DIR}")
+
 target_include_directories(libavutil
     PUBLIC
         $<BUILD_INTERFACE:${FFMPEG_DIR}>