diff --git a/CHANGES b/CHANGES
index 24fd131aa..8c1096ff9 100644
--- a/CHANGES
+++ b/CHANGES
@@ -37,6 +37,7 @@ Bugfixes:
  - GBA Video: Fix sprite mis-ordering behavior in some cases (fixes #168)
  - GBA Video: Fix window interactions with 16-color mode 0 mosaic
  - GBA Video: Fix sprite boundary conditions with mosaic
+ - Video: Fix FFmpeg crashing when the file extension is wrong
 Misc:
  - Qt: Disable sync to video by default
  - GBA: Exit cleanly on FATAL if the port supports it
diff --git a/src/platform/ffmpeg/ffmpeg-encoder.c b/src/platform/ffmpeg/ffmpeg-encoder.c
index 5f112dc88..b03b97f9d 100644
--- a/src/platform/ffmpeg/ffmpeg-encoder.c
+++ b/src/platform/ffmpeg/ffmpeg-encoder.c
@@ -196,15 +196,15 @@ bool FFmpegEncoderOpen(struct FFmpegEncoder* encoder, const char* outfile) {
 	encoder->currentVideoFrame = 0;
 	encoder->nextAudioPts = 0;
 
+	AVOutputFormat* oformat = av_guess_format(encoder->containerFormat, 0, 0);
 #ifndef USE_LIBAV
-	avformat_alloc_output_context2(&encoder->context, 0, 0, outfile);
+	avformat_alloc_output_context2(&encoder->context, oformat, 0, outfile);
 #else
 	encoder->context = avformat_alloc_context();
 	strncpy(encoder->context->filename, outfile, sizeof(encoder->context->filename));
+	encoder->context->oformat = oformat;
 #endif
 
-	encoder->context->oformat = av_guess_format(encoder->containerFormat, 0, 0);
-
 	if (acodec) {
 		encoder->audioStream = avformat_new_stream(encoder->context, acodec);
 		encoder->audio = encoder->audioStream->codec;