diff --git a/Makefile.am b/Makefile.am
index 61d9921..0559c0a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -15,6 +15,8 @@ AM_CPPFLAGS = \
 	-D__STDC_CONSTANT_MACROS \
 	@FFMPEG_CFLAGS@ \
 	@ZLIB_CPPFLAGS@ \
+	@Avisynth_CFLAGS@ \
+	@Vapoursynth_CFLAGS@ \
 	-include config.h
 AM_CXXFLAGS = -std=c++11 -fvisibility=hidden
 
diff --git a/configure.ac b/configure.ac
index b35ef80..5c3796a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -118,6 +118,15 @@ if test "$FFMPEG_WORKS" = no; then
 AC_MSG_FAILURE([cannot link with FFmpeg])
 fi
 
+if test "$enable_avisynth" = "yes"; then
+PKG_CHECK_MODULES(Avisynth, [avisynth])
+AC_SUBST([Avisynth_CFLAGS])
+fi
+
+#Let's hack vapoursynth!
+PKG_CHECK_MODULES(Vapoursynth, [vapoursynth])
+AC_SUBST([Vapoursynth_CFLAGS])
+
 src_core_libffms2_la_LDFLAGS=""
 AC_MSG_CHECKING([whether -Wl,-Bsymbolic is needed])
 if test "$enable_shared" = yes; then