diff --git a/aegisub/FFmpegSource2/ffaudiosource.cpp b/aegisub/FFmpegSource2/ffaudiosource.cpp
index 860e67e8fc987717a574af584f48191b1f6b4612..7bf4ac960ec7da0ef42b7e40928fc2a34b048a8d 100644
--- a/aegisub/FFmpegSource2/ffaudiosource.cpp
+++ b/aegisub/FFmpegSource2/ffaudiosource.cpp
@@ -453,7 +453,7 @@ int FFMatroskaAudio::DecodeNextAudioBlock(int64_t *Count, int AudioBlock, char *
 	TempPacket.data = MC.Buffer;
 	TempPacket.size = FrameSize;
 	if (Frames[AudioBlock].KeyFrame)
-		TempPacket.flags = PKT_FLAG_KEY;
+		TempPacket.flags = AV_PKT_FLAG_KEY;
 	else
 		TempPacket.flags = 0;
 
@@ -512,7 +512,7 @@ int FFHaaliAudio::DecodeNextAudioBlock(int64_t *AFirstStartTime, int64_t *Count,
 			Packet.data = Data;
 			Packet.size = pMMF->GetActualDataLength();
 			if (pMMF->IsSyncPoint() == S_OK)
-				Packet.flags = PKT_FLAG_KEY;
+				Packet.flags = AV_PKT_FLAG_KEY;
 			else
 				Packet.flags = 0;
 
diff --git a/aegisub/FFmpegSource2/ffvideosource.cpp b/aegisub/FFmpegSource2/ffvideosource.cpp
index b6a4d0812e86d401b59f7073ad79ba01580d2722..bbe8cb881c2859290ef92105ac5cb505c04bd6e0 100644
--- a/aegisub/FFmpegSource2/ffvideosource.cpp
+++ b/aegisub/FFmpegSource2/ffvideosource.cpp
@@ -528,7 +528,7 @@ int FFMatroskaVideo::DecodeNextFrame(int64_t *AFirstStartTime, char *ErrorMsg, u
 		Packet.data = MC.Buffer;
 		Packet.size = FrameSize;
 		if (FrameFlags & FRAME_KF)
-			Packet.flags = PKT_FLAG_KEY;
+			Packet.flags = AV_PKT_FLAG_KEY;
 		else
 			Packet.flags = 0;
 
@@ -769,7 +769,7 @@ int FFHaaliVideo::DecodeNextFrame(int64_t *AFirstStartTime, char *ErrorMsg, unsi
 			Packet.data = Data;
 			Packet.size = pMMF->GetActualDataLength();
 			if (pMMF->IsSyncPoint() == S_OK)
-				Packet.flags = PKT_FLAG_KEY;
+				Packet.flags = AV_PKT_FLAG_KEY;
 			else
 				Packet.flags = 0;
 
diff --git a/aegisub/FFmpegSource2/indexing.cpp b/aegisub/FFmpegSource2/indexing.cpp
index ce5656586b1d342648fb340b1b50a23f29e1de53..5cd1696a954e662dff1caf901eedee3ad09843ce 100644
--- a/aegisub/FFmpegSource2/indexing.cpp
+++ b/aegisub/FFmpegSource2/indexing.cpp
@@ -312,7 +312,7 @@ FFIndex *FFHaaliIndexer::DoIndexing(char *ErrorMsg, unsigned MsgSize) {
 			pMMF->GetPointer(&TempPacket.data);
 			TempPacket.size = pMMF->GetActualDataLength();
 			if (pMMF->IsSyncPoint() == S_OK)
-				TempPacket.flags = PKT_FLAG_KEY;
+				TempPacket.flags = AV_PKT_FLAG_KEY;
 			else
 				TempPacket.flags = 0;
 
@@ -457,7 +457,7 @@ FFIndex *FFMatroskaIndexer::DoIndexing(char *ErrorMsg, unsigned MsgSize) {
 			TempPacket.data = MC.Buffer;
 			TempPacket.size = FrameSize;
 			if ((FrameFlags & FRAME_KF) != 0)
-				TempPacket.flags = PKT_FLAG_KEY;
+				TempPacket.flags = AV_PKT_FLAG_KEY;
 			else
 				TempPacket.flags = 0;
 
@@ -600,9 +600,9 @@ FFIndex *FFLAVFIndexer::DoIndexing(char *ErrorMsg, unsigned MsgSize) {
 
 		// Only create index entries for video for now to save space
 		if (FormatContext->streams[Packet.stream_index]->codec->codec_type == CODEC_TYPE_VIDEO) {
-			(*TrackIndices)[Packet.stream_index].push_back(TFrameInfo(Packet.dts, (Packet.flags & PKT_FLAG_KEY) ? 1 : 0));
+			(*TrackIndices)[Packet.stream_index].push_back(TFrameInfo(Packet.dts, (Packet.flags & AV_PKT_FLAG_KEY) ? 1 : 0));
 		} else if (FormatContext->streams[Packet.stream_index]->codec->codec_type == CODEC_TYPE_AUDIO && (IndexMask & (1 << Packet.stream_index))) {
-			(*TrackIndices)[Packet.stream_index].push_back(TFrameInfo(Packet.dts, AudioContexts[Packet.stream_index].CurrentSample, (Packet.flags & PKT_FLAG_KEY) ? 1 : 0));
+			(*TrackIndices)[Packet.stream_index].push_back(TFrameInfo(Packet.dts, AudioContexts[Packet.stream_index].CurrentSample, (Packet.flags & AV_PKT_FLAG_KEY) ? 1 : 0));
 			AVCodecContext *AudioCodecContext = FormatContext->streams[Packet.stream_index]->codec;
 			TempPacket.data = Packet.data;
 			TempPacket.size = Packet.size;
diff --git a/aegisub/FFmpegSource2/utils.h b/aegisub/FFmpegSource2/utils.h
index ad9ce1355dc5384ae049e1c26613b8a7a63890f0..9ab240196ea723bc7e0497ee564b75ba099a6a48 100644
--- a/aegisub/FFmpegSource2/utils.h
+++ b/aegisub/FFmpegSource2/utils.h
@@ -45,6 +45,16 @@ extern "C" {
 #	include "guids.h"
 #endif
 
+
+// Compatibility with older/newer ffmpegs
+#if (LIBAVFORMAT_VERSION_INT) > (AV_VERSION_INT(52,34,0)) 
+#define codec_bmp_tags ff_codec_bmp_tags 
+#endif
+#ifndef AV_PKT_FLAG_KEY
+#define AV_PKT_FLAG_KEY PKT_FLAG_KEY
+#endif
+
+
 struct TFrameInfo {
 	FFMS_FRAMEINFO_COMMON
 	int64_t SampleStart;