diff --git a/aegisub/src/Makefile.am b/aegisub/src/Makefile.am
index 983b23a2d..9f0d85139 100644
--- a/aegisub/src/Makefile.am
+++ b/aegisub/src/Makefile.am
@@ -18,7 +18,7 @@ SUBDIRS = \
 	$(libauto3) \
 	$(libosxutil_subdir)
 
-AM_CXXFLAGS = -DAEGISUB -Iinclude @WX_CPPFLAGS@ @OPENMP_CXXFLAGS@ @LIBAVFORMAT_CFLAGS@ @LIBAVCODEC_CFLAGS@ @LIBSWSCALE_CFLAGS@ @LIBAVUTIL_CFLAGS@
+AM_CXXFLAGS = -DAEGISUB -Iinclude @WX_CPPFLAGS@ @OPENMP_CXXFLAGS@ @LIBAVFORMAT_CFLAGS@ @LIBAVCODEC_CFLAGS@ @LIBSWSCALE_CFLAGS@ @LIBAVUTIL_CFLAGS@ -I../FFmpegSource2
 
 bin_PROGRAMS = aegisub-2.1
 aegisub_2_1_LDADD = libresrc/libresrc.a $(libosxutil_lib)